L1 MICRO

Question 1

Oxidase positive, urease negative:

A. B. pertussis
B. B. parapertussis
C. B. bronchiseptica
D. None of these

Answer 1

A. B. pertussis

Question 2

Oxidase and urease positive:

A. B. pertussis
B. B. parapertussis
C. B. bronchiseptica
D. None of these

Answer 2

C. B. bronchiseptica

Question 3

Oxidase negative, urease positive:

A. B. pertussis
B. B. parapertussis
C. B. bronchiseptica
D. None of these

Answer 3

B. B. parapertussis

Question 4

Catalase positive, lactose negative, xylose positive:

A. Haemophilus aegypticus
B. Haemophilus ducreyi
C. Haemophilus parainfluenzae
D. Haemophilus influenzae

Answer 4

D. Haemophilus influenzae

Question 5

Distinct odor that is often referred to as a “chocolate cake” or “burnt chocolate” smell:

A. Burkholderia cepacia
B. Eikenella corrodens
C. Proteus sp.
D. Staphylococcus aureus

Answer 5

C. Proteus sp.

Question 6

Convex, smooth, gray, nonhemolytic; rough and mucoid variants can occur; may have a musty or mushroom odor:

A. Pseudomonas aeruginosa
B. Clostridium difficile
C. Pasteurella multocida
D. Chromobacterium violaceum

Answer 6

C. Pasteurella multocida

Question 7

Feather-edged colonies usually surrounded by zone of green discoloration; produces a highly characteristic, fruity odor resembling apples or strawberries:

A. Achromobacter denitrificans
B. Pseudomonas alcaligenes
C. Pseudomonas pseudoalcaligenes
D. Alcaligenes faecalis

Answer 7

D. Alcaligenes faecalis

Question 8

Most often, are “dead-end” hosts.

A. Ticks
B. Mice
C. Sheep
D. Human

Answer 8

D. Human

Question 9

A suspension of the test organism for use in broth dilution and disk diffusion testing is adjusted to match the turbidity of a:

A. #0.5 McFarland standard
B. #1.0 McFarland standard
C. #2.0 McFarland standard
D. #3.0 McFarland standard

Answer 9

A. #0.5 McFarland standard

Question 10

McFarland turbidity standard is prepared by mixing ________ to obtain a solution with a specific optical density.

A. 1% hydrochloric acid and 1.175% barium chloride
B. 2% hydrochoric acid and 2.175% barium chloride
C. 1% sulfuric acid and 1.175% barium chloride
D. 2% sulfuric acid and 2.175% barium chloride

Answer 10

C. 1% sulfuric acid and 1.175% barium chloride

Question 11

Culture media for Vibrio spp., EXCEPT:

A. Buffered glycerol saline
B. Cary-Blair
C. Alkaline peptone water
D. Thiosulfate citrate bile salt (TCBS) agar

Answer 11

A. Buffered glycerol saline

Question 12

Which one of the following is a prokaryote?

A. Bacteria
B. Algae
C. Protozoa
D. Fungi
E. Slime molds

Answer 12

A. Bacteria

Question 13

A group of teenagers became ill with nausea, vomiting, severe abdominal cramps, and diarrhea after eating undercooked ham- burgers from a local restaurant. Two of the teenagers were hospital- ized with hemolytic-uremic syndrome. Escherichia coli O157:H7 was isolated from the patient’s stools as well as from uncooked hamburgers. The H7 refers to which bacterial structure?

A. Lipopolysaccharide
B. Capsule
C. Flagella
D. Fimbriae
E. S-layer

Answer 13

C. Flagella

Question 14

In the fall of 2001, a series of letters containing spores of Bacillus anthracis were mailed to members of the media and to U.S. Senate offices. The result was 22 cases of anthrax, with five deaths. The heat resistance of bacterial spores, such as those of Bacillus anthracis, is partly attributable to their dehydrated state and partly to the presence of large amounts of

A. Diaminopimelic acid
B. d-Glutamic acid
C. Calcium dipicolinate
D. Sulfhydryl-containingproteins
E. Lipid A

Answer 14

C. Calcium dipicolinate

Question 15

Mycoplasma species lack which of the following components?

A. Ribosomes
B. Plasma membrane
C. Both DNA and RNA
D. Lipids
E. Peptidoglycan

Answer 15

E. Peptidoglycan

Question 16

What step in the Gram stain distinguishes between gram-positive and gram-negative organisms?

A. Fixing of the cells to the slide using heat or methanol
B. Decolorization using alcohol or acetone
C. Counterstain of the Gram stain using safranin
D. Application of the mordant, Gram’s iodine

Bailey

Answer 16

B. Decolorization using alcohol or acetone

Question 17

The unique chemical structure of the cell wall of Mycobacterium spp. is associated with the presence of:

A. N-glycolylmuramic acid and a decrease in lipid content
B. N-acetylmuramic acid and a decrease in lipid content
C. N-glycolylmuramic acid and an increase in lipid content
D. N-acetylmuramic acid and an increase in lipid content

Bailey

Answer 17

C. N-glycolylmuramic acid and an increase in lipid content

Question 18

Which of the following is the only catalase-negative, gram-positive, non-spore-forming rod that produces H2S on TSI?

A. Gardnerella sp.
B. Erysipelothrix sp.
C. Lactobacillus sp.
D. Arcanobacterium sp.

Bailey

Answer 18

B. Erysipelothrix sp.

Question 19

Which type of enrichment media is used to isolate Neisseria and Haemophilus organisms?

A. Hektoen enteric (HE) agar
B. Todd Hewitt broth
C. Regan Lowe agar
D. Chocolate agar

Bailey

Answer 19

D. Chocolate agar

Question 20

Necrotizing fasciitis is a serious infection associated with:

A. Streptococcus agalactiae
B. Streptococcus mitis
C. Streptococcus pyogenes
D. Staphylococcus epidermidis

Bailey

Answer 20

C. Streptococcus pyogenes

Question 21

A patient presents with diarrhea and abdominal cramping. The organism isolated from the stool culture is identified as S. dysenteriae (group A). The TSI reaction would have indicated:

A. K/K
B. K/NC H2S+
C. A/A
D. K/A

Bailey

Answer 21

D. K/A

Question 22

When setting up a urine culture, a calibrated loop is used that delivers a specific amount of urine to the media plate. What is that amount?

A. 0.01 or 0.001 mL of urine
B. 0.10 or 0.01 mL of urine
C. 0.001 or 0.0001 mL of urine
D. None of the above is correct

Answer 22

A. 0.01 or 0.001 mL of urine

Question 23

ANSWER & IDENTIFY THE ORGANISM
An isolate recovered from a vaginal culture obtained from a 25-year-old female patient who is 8 months pregnant is shown to be a gram-positive cocci, catalase negative, and β-hemolytic on blood agar. Which tests are needed for further identification?

A. Optochin, bile solubility, PYR
B. Bacitracin, CAMP, PYR
C. Methicillin, PYR, trehalose
D. Coagulase, glucose, PYR

Answer 23

S. agalactiae
B. Bacitracin, CAMP, PYR

Question 24

ANSWER & IDENTIFY THE ORGANISM
A wound (skin lesion) specimen obtained from a newborn grew predominantly β-hemolytic colonies of gram-positive cocci on 5% sheep blood agar. The newborn infant was covered with small skin eruptions that gave the appearance of a “scalding of the skin.” The gram-positive cocci proved to be catalase positive.

Which tests should follow for the appropriate identification?

A. Optochin, bile solubility, PYR
B. Coagulase, glucose fermentation, DNase
C. Bacitracin, PYR, 6.5% salt broth
D. CAMP, bile-esculin, 6.5% salt broth

Answer 24

S.aureus
B. Coagulase, glucose fermentation, DNase

Question 25

ANSWER & IDENTIFY THE ORGANISM
A sputum specimen from an 89-year-old male patient with suspected bacterial pneumonia grew a predominance of gram-positive cocci displaying alpha-hemolysis on 5% sheep blood agar. The colonies appeared donut shaped and mucoidy and tested negative for catalase. The most appropriate tests for a final identification are:

A. Coagulase, glucose fermentation, lysostaphin
B. Penicillin, bacitracin, CAMP
C. Optochin, bile solubility, PYR
D. Bile esculin, hippurate hydrolysis

Answer 25

S.pneumoniae
C. Optochin, bile solubility, PYR

Question 26

Small, gray, glistening; colonies tend to dip down in the center and RESEMBLE A DOUGHNUT (umbilicated) as they age; if organism has a polysaccharide capsule, colony may be mucoid; ALPHA-HEMOLYTIC:

A. Streptococcus pyogenes
B. Streptococcus agalactiae
C. Streptococcus pneumoniae
D. Staphylococcus aureus

Answer 26

C. Streptococcus pneumoniae

Question 27

Neonatal meningitis is an uncommon but significant disease. Two important causes of this disease may be somewhat difficult to differentiate on preliminary observation.
Which of the following sets of tests provide the best differentiation of Streptococcus agalactiae from Listeria monocytogenes?

A. Gram-stained smear, oxidase, and optochin
B. Gram-stained smear, catalase, and motility
C. CAMP test, hydrogen sulfide production,beta-hemolysis
D. Reverse CAMP, gram-stained smear, beta-hemolysis

Answer 27

B. Gram-stained smear, catalase, and motility

Question 28

A gram-positive coccus that is catalase positive, nonmotile, lysostaphin resistant, and modified oxidase positive is best identified as a member of the genus:

A. Micrococcus
B. Lactococcus
C. Pediococcus
D. Staphylococcus

Answer 28

A. Micrococcus

Question 29

A light yellow colony from a skin lesion grew aerobically and tested as catalase positive and coagulase negative. The organism gram stained as positive cocci in clusters. The organism was modified oxidase positive, bacitracin susceptible and resistant to lysostaphin. What is the identification of this organism?

A. Staphylococcus aureus
B. Micrococcus luteus
C. Staphylococcus epidermidis
D. Peptostreptococcus anaerobius

Answer 29

B. Micrococcus luteus

Question 30

Staphylococcus saprophyticus is best differentiated from Staphylococcus epidermidis by resistance to:

A. 5 μg of lysostaphin
B. 5 μg of novobiocin
C. 10 units of penicillin
D. 0.04 unit of bacitracin

Answer 30

B. 5 μg of novobiocin

Question 31

Which of the following organisms, to date, considered universally susceptible to penicillin?

A. Haemophilus influenzae
B. Neisseria gonorrhoeae
C. Streptococcus pyogenes
D. Corynebacterium diphtheriae

Answer 31

C. Streptococcus pyogenes

Question 32

Seventy (70) percent recirculated to the cabinet work area through HEPA; 30% balance can be exhausted through HEPA back into the room or to outside through a canopy unit:

A. BSC Class I
B. BSC Class II, A1
C. BSC Class II, B1
D. BSC Class II, B2

Answer 32

B. BSC Class II, A1

Question 33

Thirty (30) percent recirculated, 70% exhausted. Exhaust cabinet air must pass through a dedicated duct to the outside through a HEPA filter.

A. BSC Class I
B. BSC Class II, A1
C. BSC Class II, B1
D. BSC Class II, B2

Answer 33

C. BSC Class II, B1

Question 34

No recirculation; total exhaust to the outside through a HEPA filter.

A. BSC Class I
B. BSC Class II, A1
C. BSC Class II, B1
D. BSC Class II, B2

Answer 34

D. BSC Class II, B2

Question 35

An isolate of Staphylococcus aureus was cultured from an ulcer obtained from the leg of a diabetic 79-year-old female patient. The organism showed resistance to methicillin. Additionally, this isolate should be tested for resistance or susceptibility to:

A. Erythromycin
B. Gentamicin
C. Vancomycin
D. Kanamycin

Answer 35

C. Vancomycin

Question 36

The major toxicities of this antibiotic are RED MAN SYNDROME, nephrotoxicity, and ototoxicity:

A. Choramphenicol
B. Penicillin
C. Sulfonamide
D. Vancomycin

Answer 36

D. Vancomycin

Question 37

A sheep blood agar plate inoculated with 0.001 mL of urine grows 70 colonies of Staphylococcus aureus. How many colony forming units per mL of urine should be reported?

A. 70
B. 700
C. 7,000
D. 70,000

Answer 37

D. 70,000

Question 38

The minimum concentration of antimicrobial agent needed to prevent visually discernible growth of a bacterial or fungal suspension.

A. Minimum bactericidal concentration (MBC)
B. Minimum inhibitory concentration (MIC)
C. Both of these
D. None of these

Answer 38

B. Minimum inhibitory concentration (MIC)

Question 39

The minimum concentration of antimicrobial agent needed to yield a 99.9% reduction in viable colony-forming units of a bacterial or fungal suspension.

A. Minimum bactericidal concentration (MBC)
B. Minimum inhibitory concentration (MIC)
C. Both of these
D. None of these

Answer 39

A. Minimum bactericidal concentration (MBC)

Question 40

The proper blood-to-broth ratio for blood cultures to reduce the antibacterial effect of serum in adults is:

A. 1:2
B. 1:3
C. 1:10
D. 1:30

Answer 40

C. 1:10

Question 41

In the Kirby-Bauer disc diffusion susceptibility test, which variable is critical when testing Pseudomonas species for antibiotic susceptibility to aminoglycosides?

A. Incubation temperature
B. Duration of incubation
C. Cation content of media
D. Depth of agar

Answer 41

C. Cation content of media

Question 42

In disk diffusion susceptibility testing, as an antimicrobial agent diffuses away from the disk, the concentration of antibiotic is:

A. Increased
B. Decreased
C. Unchanged
D. Inoculum dependent

Answer 42

B. Decreased

Question 43

PROGRESSIVE ENDOPHTHALMITIS
It is a serious pathogen of the eye, causing progressive endophthalmitis:

A. Bacillus anthracis
B. Bacillus cereus
C. Bacillus subtilis
D. Bacillus thurigiensis

Answer 43

B. Bacillus cereus

Question 44

A sputum culture from an alcoholic seen in the ER grows gray, mucoid, stringy colonies on sheep blood agar. The isolate grows readily on MacConkey agar and forms mucoid, dark pink colonies. The colonies yield the following test results:
ONPG +
Indole -
Glucose +
Oxidase -
Citrate +
VP +
The organism is most likely:

A. Edwardsiella tarda
B. Klebsiella pneumoniae
C. Escherichia coli
D. Proteus vulgaris

Answer 44

B. Klebsiella pneumoniae

Question 45

Plesiomonas shigelloides is a relatively new member of the family Enterobacteriaceae. What characteristic separates it from other members of the Enterobacteriaceae?

A. It is oxidase positive.
B. It ferments glucose.
C. It produces pyocyanin
D. it requires 10% CO2 for growth

Answer 45

A. It is oxidase positive.

Question 46

Which of the following tests is most helpful in differentiating C.jejuni from the other Campylobacter spp.?

A. Nitrate reduction
B. Urease activity
C. Hippurate hydrolysis
D. Susceptibility to nalidixic acid

Answer 46

C. Hippurate hydrolysis

Question 47

A positive hippurate hydrolysis is a characteristic of:

A. Campylobacter coli
B. Campylobacter jejuni
C. Campylobacter lari
D. Campylobacter fetus

Answer 47

B. Campylobacter jejuni

Question 48

The ETHANOL SHOCK procedure is used to differentiate:

A. Actinomyces and Bifidobacterium spp.
B. Prevotella and Porphyromonas spp.
C. Clostridium and Bacteroides spp.
D. Bacteroides and Actinomyces spp.

Bailey

Answer 48

C. Clostridium and Bacteroides spp.

Question 49

Which of the following bacteria is able to hydrolyze urea via urease production, which results in an increase in urine pH that is toxic to kidney cells and stimulates the formation of kidney stones?

A. E. coli
B. Proteus
C. S. aureus
D. Pseudomonas aeruginosa

Bailey

Answer 49

B. Proteus

Question 50

Loeffler’s agar slant is a special culture medium used to recover which organism?

A. Streptococcus pyogenes
B. Corynebacterium diphtheriae
C. Bordetella pertussis
D. Neisseria meningitidis

Bailey

Answer 50

B. Corynebacterium diphtheriae

Question 51

Yellow ground-glass colonies on cycloserine cefoxitin fructose agar (CCFA):

A. Bacillus anthracis
B. Bacillus cereus
C. Clostridium difficile
D. Clostridium perfringens

Answer 51

C. Clostridium difficile

Question 52

EYE CULTURE, GRAM-POSITIVE, AEROBIC, MOTILE & BETA-HEMOLYTIC
A large, aerobic, beta-hemolytic, gram-positive rod is isolated from an eye culture. Subsequent testing reveals it is motile and produces a wide zone on egg yolk agar. The most likely identification of this organism is:

A. Bacillus anthracis
B. Escherichia coli
C. Bacillus cereus
D. Clostridium perfringens

Bailey

Answer 52

C. Bacillus cereus

Question 53

A large, aerobic, gram-positive, spore-forming rod is isolated from a blood culture. It can be further confirmed as B. anthracis if it is:

A. Hemolytic and motile
B. Hemolytic and nonmotile
C. Nonhemolytic and motile
D. Nonhemolytic and nonmotile

Bailey

Answer 53

D. Nonhemolytic and nonmotile

Question 54

Which of the following conditions is viewed as a risk factor for systemic disease caused by Pasteurella multocida subsp. multocida?

A. Liver cirrhosis
B. End-stage renal disease
C. Hyperlipidemia
D. Hereditary hemochromatosis

Bailey

Answer 54

A. Liver cirrhosis

Question 55

What is the primary etiologic agent in children with epiglottitis?

A. Haemophilus influenzae
type b
B. Corynebacterium diphtheriae
C. Streptococcus pyogenes
D. Staphylococcus aureus

Bailey

Answer 55

A. Haemophilus influenzae type b

Question 56

ANSWER & INDICATE ORGANISM
The organism most commonly associated with otitis media infections is associated with which of the following positive test results?

A. Coagulase
B. VP
C. Optochin
D. Bacitracin

Answer 56

S. pneumoniae
C. Optochin

Question 57

The specimen of choice for the isolation of Bordetella pertussis from a suspected case of whooping cough is:

A. Blood
B. CSF
C. Nasopharyngeal swab
D. Throat swab

Answer 57

C. Nasopharyngeal swab

Question 58

Twenty patients on a surgical ward develop urinary tract infections after catheterization. In each instance, the isolated organism grows on sheep BAP as large, gray colony, and on MacConkey agar as a large, flat and pink colony. The oxidase-negative rod produces the same biotype and is resistant only to tetracycline. Additional biochemical results are as follows:
Phenylalanine deaminase (PAD): negative
Urease: negative
Hydrogen sulfide (H2S): negative
Lysine decarboxylase: negative
Ornithine decarboxylase: positive
Indole: positive
Citrate: negative

The most probable identity of this organism is:

A. Escherichia coli
B. Enterobacter cloacae
C. Enterobacter aerogenes
D. Proteus vulgaris

Answer 58

A. Escherichia coli

Question 59

A discharge from an infected ear grows a colorless colony type on MacConkey agar that swarms on sheep BAP. This oxidase-negative, gram-negative rod is resistant to tetracycline and colistin on a routine Kirby-Bauer antimicrobial susceptibility test and gives the following biochemical reactions:
Phenylalanine deaminase (PAD): positive
Hydrogen sulfide (H2S): positive
Urease: positive
Lysine: negative
Ornithine: positive
Indole: negative
Citrate: positive

The organism described is:

A. Citrobacter freundii
B. Morganella morganii
C. Proteus mirabilis
D. Proteus vulgaris

Answer 59

C. Proteus mirabilis

Question 60

Which Mycobacterium is associated with Crohn’s disease?

A. M. marinum
B. M. paratuberculosis
C. M. avium
D. M. gordonae

Answer 60

B. M. paratuberculosis

Question 61

A single ASO titer is considered to be moderately elevated if the titer is at least ____ Todd units in an adult.

A. 200 Todd units
B. 240 Todd units
C. 320 Todd units
D. 340 Todd units

Answer 61

B. 240 Todd units

Question 62

A single ASO titer is considered to be moderately elevated if the titer is at least ____ Todd units in a child.

A. 200 Todd units
B. 240 Todd units
C. 320 Todd units
D. 340 Todd units

Answer 62

C. 320 Todd units

Question 63

Which Brucella species may require CO2 for growth, is urea positive in 2 hours, and is inhibited by thionine dye?

A. Brucella abortus
B. Brucella melitensis
C. Brucella suis
D. Brucella canis

Answer 63

A. Brucella abortus

Question 64

Brucella isolate that does not produce H2S, does not require CO2, and is not inhibited by thionine and basic fuchsin is probably which species of Brucella?

A. Brucella canis
B. Brucella abortus
C. Brucella suis
D. Brucella melitensis

Answer 64

D. Brucella melitensis

Question 65

Which is the most appropriate nonselective medium for recovery of mycobacteria from a heavily contaminated specimen?

A. Löwenstein–Jensen agar
B. Middlebrook 7H10 agar
C. Petragnani’s agar
D. American Thoracic Society medium

Answer 65

C. Petragnani’s agar

Question 66

A Haemophilus spp., recovered from a throat culture obtained from a 59-year-old male patient undergoing chemotherapy, required hemin (X factor) and NAD (V factor) for growth. This species also HEMOLYZED horse erythrocytes on blood agar. What is the most likely species?

A. H. ducreyi
B. H. parahaemolyticus
C. H. haemolyticus
D. H. aegyptius

Answer 66

C. H. haemolyticus

Question 67

Acid-fast positive bacilli were recovered from the sputum of a 79-year-old man who had been treated for pneumonia. Which of the following test reactions after 3 weeks of incubation on Löwenstein–Jensen agar are consistent with Mycobacterium tuberculosis?

A. Niacin +, Nitrate reduction +, Photochromogen negative
B. Niacin negative, Optochin +, Catalase +
C. PYR +, Urease +, Bacitracin +
D. Ampicillin resistant, Penicillin resistant

Answer 67

A. Niacin +, Nitrate reduction +, Photochromogen negative

Question 68

A gram-positive bacillus was isolated from a wound specimen and had the following characteristics: double zone of β hemolysis, lecithinase positive, lipase negative, spot indole negative. What is the most likely identification of this organism?

A. Clostridium perfringens
B. Clostridium ramosum
C. Clostridium septicum
D. Clostridium tetani

Answer 68

A. Clostridium perfringens

Question 69

A lymph node biopsy obtained from a 30-year-old male patient was submitted to the microbiology laboratory for a culture and AFB smear for mycobacteria. The specimen was fixed in formalin. This specimen should be:

A. Accepted for AFB smear and cultured
B. Rejected
C. Held at room temperature for 24 hours and then cultured
D. Cultured for anaerobes only

Answer 69

B. Rejected

Question 70

A 14-year-old emergency department patient had been to the doctor’s office 2 days previously with abdominal pain, diarrhea, and a low-grade fever. He was diagnosed with pseudoappendicular syndrome. Cultures from the stool containing blood and WBCs showed the following results:
AEROBIC GRAM-NEGATIVE RODS ON MACCONKEY AGAR (CLEAR COLONIES)
Campy agar = No growth
Lactose = Neg
Indole = Neg
Motility 37°C = Neg
Motility 22°C = +
Sucrose = +
VP = Neg
Citrate = Neg
H2S = Neg
Hektoen agar = NF

What is the most likely identification?

A. Yersinia enterocolitica
B. Salmonella spp.
C. Shigella spp.
D. Escherichia coli

Answer 70

A. Yersinia enterocolitica

Question 71

Which biochemical tests should be performed in order to identify colorless colonies growing on MacConkey agar (swarming colonies on blood agar) from a catheterized urine specimen?

A. Indole, phenylalanine deaminase, and urease
B. Glucose, oxidase, and lactose utilization
C. Phenylalanine deaminase and bile solubility
D. H2S and catalase

Answer 71

A. Indole, phenylalanine deaminase, and urease

Question 72

An 80-year-old male patient was admitted to the hospital with a fever of 102°F. A sputum culture revealed many gram-negative rods on MacConkey agar and blood agar. The patient was diagnosed with pneumonia. The following biochemical results were obtained from the culture:
H2S = Neg
Citrate = + ✅
Motility = Negative ✅
Lactose = +
Indole = + ✅
Resistance to ampicillin and carbenicillin
Urease = +
VP = + ✅

What is the most likely identification?

A. Klebsiella oxytoca
B. Proteus mirabilis
C. Escherichia coli
D. Klebsiella pneumoniae

Answer 72

A. Klebsiella oxytoca

Question 73

Campylobacter are:

A. Small, curved, motile, gram-positive bacilli
B. Small, curved, motile gram-negative bacilli
C. Small, curved, nonmotile, gram-negative bacilli
D. Small, curved, nonmotile, gram-negative bacilli

Bailey

Answer 73

B. Small, curved, motile gram-negative bacilli

Question 74

Which organism produces the CAMP factor enhancing beta hemolysis in the presence of the S. aureus beta lysin?

A. group A streptococci
B. group B streptococci
C. group C streptococci
D. group D streptococci

Bailey

Answer 74

B. group B streptococci

Question 75

What substance added to the antigen in the RPR test allows for more macroscopically visible flocculation?

A. Latex particles
B. Extracellular antigens
C. Heparin-magnesium chloride particles
D. Charcoal particles

Bailey

Answer 75

D. Charcoal particles

Question 76

All of the following media used for the cultivation of Micrococcaceae are selective except:

A. 5% sheep blood agar
B. Phenyl-ethyl alcohol agar
C. Mannitol salt agar
D. Colistin nalidixic acid agar

Bailey

Answer 76

A. 5% sheep blood agar

Question 77

Which of the following has been recognized in postinfectious complications of a Campylobacter jejuni infection?

A. Guillain-Barré syndrome
B. Chronic pulmonary disease
C. Encephalitis
D. Endocarditis

Answer 77

A. Guillain-Barré syndrome

Question 78

Sulfur granules in a clinical specimen indicate the presence of:

A. Clostridium spp.
B. Fusobacterium spp.
C. Actinomyces spp.
D. Peptostreptococcus spp.

Answer 78

C. Actinomyces spp.

Question 79

A gram-positive coccus that is catalase positive, nonmotile, lysostaphin resistant, and modified oxidase positive is best identified as a member of the genus:

A. Micrococcus
B. Lactococcus
C. Pediococcus
D. Staphylococcus

Answer 79

A. Micrococcus

Question 80

The production of H2S is one characteristic used to differentiate which of the aerobic gram-positive bacilli?

A. Corynebacterium
B. Erysipelothrix
C. Lactobacillus
D. Nocardia

Answer 80

B. Erysipelothrix

Question 81

A negative PYR test is demonstrated by:

A. Enterococcus faecalis
B. Enterococcus faecium
C. Streptococcus pyogenes
D. Viridans streptococci

Answer 81

D. Viridans streptococci

Question 82

Cystine-tellurite blood agar plates are recommended for the isolation of:

A. Corynebacterium diphtheriae
B. Streptococcus agalaciae
C. Streptococcus pyogenes
D. Group D streptococci

Answer 82

A. Corynebacterium diphtheriae

Question 83

Which microorganism will grow only on culture media supplemented with either cysteine or cystine?

A. Actinobacillus lignieresii
B. Bartonella bacilliformis
C. Francisella tularensis
D. Kingella kingae

Answer 83

C. Francisella tularensis

Question 84

Severe disseminated intravascular coagulation often complicates cases of septicemia caused by:

A. Acinetobacte rsp.
B. Moraxella sp.
C. Neisseria gonorrhoeae
D. Neisseria meningitidis

Answer 84

D. Neisseria meningitidis

Question 85

The symptom of diffuse, watery diarrhea that produces a relatively clear stool containing mucus flecks is suggestive of an infection caused by:

A. Enterohemorrhagic Escherichia coli
B. Shigella dysenteriae
C. Vibrio cholerae
D. Yersinia enterocolitica

Answer 85

C. Vibrio cholerae

Question 86

The classic toxigenic strains of which serogroup are implicated in epidemic infections of Vibrio cholerae?

A. O1
B. O2
C. O3
D. O4

Answer 86

A. O1

Question 87

A positive indole reaction is characteristic of:

A. Escherichia coli
B. Proteus mirabilis
C. Salmonella choleraesuis
D. Serratia marcescens

Answer 87

A. Escherichia coli

Question 88

ANSWER & IDENTIFY THE TEST
Of the following microorganisms, which one will turn a dark purple when tetramethyl-p-phenylenediaminehydrochloride is applied?

A. Acinetobacter baumannii
B. Stenotrophomonas maltophilia
C. Moraxella catarrhalis
D. Yersinia enterocolitica

Answer 88

Oxidase Test
C. Moraxella catarrhalis

Question 89

Large, nonpigmented or gray, opaque, smooth; friable “HOCKEY PUCK” consistency; colony may be moved intact over surface of CAP:

A. Neisseria gonorrhoeae
B. Neisseria meningitidis
C. Neisseria elongata
D. Moraxella catarrhalis

Answer 89

D. Moraxella catarrhalis

Question 90

When clinical specimens are processed for the recovery of Mycobacterium tuberculosis, the generally recommended method for digestion and decontamination of the sample is:

A. 6% NaOH
B. HCl
C. NALC-NaOH
D. Trisodium phosphate

Answer 90

C. NALC-NaOH

Question 91

Which one of the following drugs is NOT considered as primary antimycobacterial therapy?

A. Isoniazid
B. Kanamycin
C. Rifampin
D. Pyrazinamide

Answer 91

B. Kanamycin

Question 92

Which of the following is the most potent bacterial exotoxin known?

A. Botulinum toxin
B. Erythrogenic toxin
C. C. difficile toxin B
D. C.perfringens alpha-toxin

Answer 92

A. Botulinum toxin

Question 93

The minimum bactericidal concentration (MBC) of an antimicrobial agent is defined as the lowest concentration of that antimicrobial agent that kills at least:

A. 95.5%
B. 97%
C. 99.9%
D. 100%

Answer 93

C. 99.9%

Question 94

The pH of the agar used for the Kirby-Bauer test should be:

A. 7.0 to 7.2
B. 7.2 to 7.4
C. 7.4 to 7.6
D. 7.6 to 7.8

Answer 94

B. 7.2 to 7.4

Question 95

Chloramphenicol is an important antimicrobial agent for the treatment of meningitis as well as several other serious infections. Unfortunately, chloramphenicol exhibits significant complications that limit its clinical usefulness. These effects include:

A. Allergic reactions and anaphylaxis
B. Bone marrow suppression and aplastic anemia
C. Significant gastrointestinal manifestations
D. Photosensitivity

Answer 95

B. Bone marrow suppression and aplastic anemia

Question 96

PHENYLANINE DEAMINASE TEST
The ability of a microorganism to deaminate phenylalanine can be assessed by inoculating a phenylalanine agar slant with the test organism. Following incubation, if the organism is positive, a green color develops with the addition of

A. 10% ferric chloride
B. 2% sulfanilamide
C. 2N sodium carbonate
D. 5% alpha-naphthol

Answer 96

A. 10% ferric chloride

Question 97

VOGES-PROSKAUER TEST
What two reagents must be added to determine if the bacterium is VP positive?

A. Creatine and 1N HCl
B. 10% FeCl3 and alpha-naphthol
C. Kovac’s reagent and zinc dust
D. Alpha-naphthol and 40% KOH

Answer 97

D. Alpha-naphthol and 40% KOH

Question 98

In the RPR test, what is the gauge of the needle for antigen delivery?

A. 16
B. 18
C. 20
D. 21

Answer 98

C. 20

Question 99

Speed and time of rotation for serum VDRL test:

A. 100 rpm for 4 minutes
B. 100 rpm for 8 minutes
C. 180 rpm for 4 minutes
D. 180 rpm for 8 minutes

Answer 99

C. 180 rpm for 4 minutes

Question 100

Speed and time of rotation for CSF VDRL test:

A. 100 rpm for 4 minutes
B. 100 rpm for 8 minutes
C. 180 rpm for 4 minutes
D. 180 rpm for 8 minutes

Answer 100

D. 180 rpm for 8 minutes

Question 101

Speed and time of rotation for RPR:

A. 100 rpm for 4 minutes
B. 100 rpm for 8 minutes
C. 180 rpm for 4 minutes
D. 180 rpm for 8 minutes

Answer 101

B. 100 rpm for 8 minutes

Question 102

Most common cause of ASEPTIC MENINGITIS, an inflammation of the brain parenchyma:

A. Arenavirus
B. Cytomegalovirus
C. Enterovirus
D. Herpes simplex virus 2

Answer 102

C. Enterovirus

Question 103

Subacute sclerosing panencephalitis (SSPE) is a progressive, disabling, and deadly brain disorder related to ____ infection.

A. Chickenpox (varicella)
B. Smallpox (variola major)
C. German measles (rubella)
D. Measles (rubeola)

Answer 103

D. Measles (rubeola)

Question 104

Germ tube formation is seen with which two yeasts?

A. C. albicans, C. neoformans
B. C. albicans, C. parapsilosis
C. C. glabrata, C. parapsilosis
D. C. albicans, C. dubliniensis
E. C. glabrata, C. dubliniensis

Answer 104

D. C. albicans, C. dubliniensis

Question 105

Trichophyton rubrum and T. mentagrophytes may be differentiated by the:

A. Consistently different appearance of their colonies
B. Endothrix hair infection produced by T. rubrum
C. Fluorescence of hairs infected with T. rubrum
D. In vitro hair penetration by T. mentagrophytes

Answer 105

D. In vitro hair penetration by T. mentagrophytes

Question 106

Added to SDA to inhibit most contaminating bacteria:

A. Dextrose
B. Chloramphenicol
C. Cycloheximide
D. Nystatin

Answer 106

B. Chloramphenicol

Question 107

Added to SDA to inhibit saprophytic fungi:

A. Dextrose
B. Chloramphenicol
C. Cycloheximide
D. Nystatin

Answer 107

C. Cycloheximide

Question 108

Include all the COMMON AGENTS OF INFECTIOUS DISEASE, as well as HIV, hepatitis B virus and Salmonella organisms:

A. BSL-1 agents
B. BSL-2 agents
C. BSL-3 agents
D. BSL-4 agents

Answer 108

B. BSL-2 agents

Question 109

EXOTIC AGENTS that are considered high risk and cause life-threatening disease:

A. BSL-1 agents
B. BSL-2 agents
C. BSL-3 agents
D. BSL-4 agents

Answer 109

D. BSL-4 agents

Question 110

TAKE NOTE OF THE OXIDASE REACTION
A stool specimen is submitted for culture. The results are: beta- hemolytic on blood agar, NLF on MacConkey, oxidase positive, bull’s-eye appearance on CIN agar.

This organism is most likely:

A. A. hydrophilia
B. Y. enterocolitica
C. C. violaceum
D. G. hollisae

Bailey

Answer 110

A. A. hydrophilia

Question 111

Which mycobacterium of the M. tuberculosis complex fails to grow in culture and has a characteristic “croissant-like” morphology in stained smears?

A. M. africanum
B. M. microti
C. M. bovis
D. M. leprae

Answer 111

B. M. microti

Question 112

The following results were obtained from a pure culture of gram-negative rods recovered from the pulmonary secretions of a 10-year-old cystic fibrosis patient with pneumonia:
Oxidase = +
Motility = +
Glucose OF (open) = +
Gelatin hydrolysis = +
Growth at 42°C = +
Flagella = + (polar, monotrichous)

Which is the most likely organism?

A. Burkholderia pseudomallei
B. Pseudomonas stutzeri
C. Burkholderia cepacia
D. Pseudomonas aeruginosa

Answer 112

D. Pseudomonas aeruginosa

Question 113

A 17-year-old female with cystic fibrosis is diagnosed with pneumonia. A sputum sample grew gram-negative bacilli with yellow ✅, smooth colonies that have the following biochemical reactions:
Oxidase: positive ✅
TSI: alk/alk
Glucose: oxidized
Fluorescence: negative
Lysine decarboxylase: positive

The most likely organism is:

A. Burkholderia cepacia
B. Klebsiella pneumoniae
C. Shewanella putrefaciens
D. Stenotrophomonas maltophilia

Answer 113

A. Burkholderia cepacia

Question 114

OXIDASE NEG, LAVENDER GREEN PIGMENT, LDC +
A sputum culture from a 13-year-old cystic fibrosis patient grew a predominance of short, gram-negative rods that tested oxidase negative. On MacConkey, chocolate, and blood agar plates, the organism appeared to have a lavender-green pigment. Further testing showed:
Motility = +
Glucose = + (oxidative)
Lysine decarboxylase = +
DNase = +
Maltose = + (oxidative)
Esculin hydrolysis = +

What is the most likely identification?

A. Stenotrophomonas maltophilia
B. Acinetobacter baumannii
C. Pseudomonas aeruginosa
D. Burkholderia (P.) cepacian

Answer 114

A. Stenotrophomonas maltophilia

Question 115

Unopened, sliced BACON, packaged in material somewhat highly resistant to oxygen permeability, is spoiled mostly by

A. Lactobacilli
B. Micrococci
C. Fecal Streptococci
D. Molds

Answer 115

A. Lactobacilli

Question 116

Access to the laboratory is limited or restricted, and there must be a biohazard sign posted at the entrance of the laboratory:

A. BSL-1
B. BSL-2
C. BSL-3
D. BSL-4

Answer 116

A. BSL-1

Question 117

Access to the laboratory is limited when work is being conducted. The laboratory director is ultimately responsible for determining who may enter or work in the laboratory.

A. BSL-1
B. BSL-2
C. BSL-3
D. BSL-4

Answer 117

B. BSL-2

Question 118

Laboratory should be separated from the other parts of the building and be accessed through two self-closing doors. An ANTEROOM may be used for access.

A. BSL-1
B. BSL-2
C. BSL-3
D. BSL-4

Answer 118

C. BSL-3

Question 119

The BSL facility either is located in a separate building or is in an isolated zone within a building.

A. BSL-1
B. BSL-2
C. BSL-3
D. BSL-4

Answer 119

D. BSL-4

Question 120

Which of the ff. makes Mannitol Salt Agar (MSA) selective?

A. Mannitol
B. Phenol red
C. Neutral red
D. Sodium chloride

Answer 120

D. Sodium chloride

Question 121

Nonmotile, non-spore-forming, obligate aerobe, acid-fast bacillus that often appears beaded or unstained using Gram stain; it is distinguished by its ability to form stable mycolate complexes with arylmethane dyes (carbolfuchsin, auramine, and rhodamine):

A. Streptococcus pneumoniae
B. Neisseria meningitidis
C. Hemophilus influenzae
D. Mycobacterium tuberculosis

Answer 121

D. Mycobacterium tuberculosis

Question 122

Which of the following Mycobacterium is most noted for being associated with patients with acquired immunodeficiency syndrome?

A. M. avium-intracellulare complex
B. M. marinum
C. M. kansasii
D. M. bovis

Answer 122

A. M. avium-intracellulare complex

Question 123

Calcofluor white is a colorless dye that binds with which of the following structures?

A. Cell wall containing mycolic acid
B. Chitin
C. Peptidoglycan layer
D. Metachromatic granules

Answer 123

B. Chitin

Question 124

Which of the following tests detects the production of mixed acids as a result of subsequent metabolism of pyruvate?

A. Methyl red test
B. Voges-Proskauer test
C. Citrate test
D. Indole test

Answer 124

A. Methyl red test

Question 125

The metabolism of glucose to pyruvate by members of the family Enterobacteriaceae is via the Embden-Meyerhof “Parnas” (EMP) pathway. The subsequent metabolism of pyruvate shows this reaction: Glucose → Pyruvate → Acetylmethylcarbinol (acetoin) → 2,3-Butanediol. This reaction is the basis for the:

A. Oxidase reaction
B. Methyl red test
C. Indole test
D. Voges-Proskauer test

Answer 125

D. Voges-Proskauer test

Question 126

Tryptophan broth is inoculated and incubated 24 hours. After incubation, Kovac’s reagent is added. A red color develops at the surface of the broth. What product of metabolism was formed?

A. Mixed acids
B. Malonate
C. Phenylpyruvate
D. Indole

Answer 126

D. Indole

Question 127

Which of the listed antimicrobials act on cell wall biosynthesis?

A. β-Lactams and glycopeptides
B. Tetracycline and streptomycin
C. Macrolides and phenicols
D. Fluoroquinolone and sulfamethoxazole

Answer 127

A. β-Lactams and glycopeptides

Question 128

Extended-spectrum beta-lactamases (ESBLs)
ESBL-producing isolates should be considered resistant to which of the following agents?

A. Cephalosporins, penicillins, and aztreonam
B. Cephalosporins, penicillins, and aminoglycosides
C. Cephalosporins, penicillins, and β-lactamase inhibitors
D. Penicillins and aminoglycosides

Answer 128

A. Cephalosporins, penicillins, and aztreonam

Question 129

A newborn female becomes febrile and will not feed for about an hour after birth. A gram-positive rod is recovered from blood cultures from the newborn. The isolate has the characteristics listed below:
Weakly β-hemolytic on SBA
Gram-positive bacilli, no spores observed
Catalase positive
Hydrogen sulfide negative
Motile at room temperature

What is the most likely identity of the isolate?

A. Erysipelothrix rhusiopathiae
B. Listeria monocytogenes
C. Corynebacterium ureilyticum
D. Gardnerella vaginalis

Answer 129

B. Listeria monocytogenes

Question 130

A commercial fisherman with red sores on his hands was seen by his physician. Biopsy and culture of one of the lesions grew an organism with the characteristics listed below:
Nonhemolytic on SBA
Gram-positive bacilli, no spores observed
Catalase negative
Hydrogen sulfide production positive
Growth in gelatin resembled a test-tube brush

What is the most likely identification?

A. Rhodococcus equi
B. Listeria monocytogenes
C. Lactobacillus acidophilus
D. Erysipelothrix rhusiopathiae

Answer 130

D. Erysipelothrix rhusiopathiae

Question 131

The causative agent of plague is most often transmitted to humans by:

A. Fleas
B. Mosquitos
C. Dog bites
D. Inhalation

Answer 131

A. Fleas

Question 132

Which of the following viruses is implicated along with Epstein–Barr virus as a cause of infectious mononucleosis?

A. Cytomegalovirus (CMV)
B. Coxsackie A virus
C. Coxsackie B virus
D. Hepatitis B virus

Answer 132

A. Cytomegalovirus (CMV)

Question 133

An immunocompromised patient was admitted to the hospital with a diagnosis of HEMORRHAGIC CYSTITIS. Which combination of virus and specimen would be most appropriate to diagnose a viral cause of this disorder?

A. BK virus—urine
B. Human papilloma virus—skin
C. Hepatitis B virus—serum
D. Epstein–Barr virus—serum

Answer 133

A. BK virus—urine

Question 134

Kaposi sarcoma is associated with infection by:

A. Adenovirus
B. Cytomegalovirus
C. Hepatitis E virus
D. Human herpes virus 8

Answer 134

D. Human herpes virus 8

Question 135

Which characteristic is most useful in differentiating Citrobacter and Salmonella?

A. H2S production
B. Indole production
C. Lysine decarboxylase
D. Urease production

Answer 135

C. Lysine decarboxylase

Question 136

A fungal specimen isolated from the bone marrow of a patient with a pulmonary infection showed tuberculate macroconidia at 30C and yeastlike cells at 37C. Identify the most likely dimorphic fungi with these characteristics:

A. Aspergillus fumigatus
B. Blastomyces dermatitidis
C. Histoplasma capsulatum
D. Trichophyton mentagrophytes

Answer 136

C. Histoplasma capsulatum

Question 137

A mold grown at 25C exhibited delicate septate hyaline hyphae and many conidiophores extending at right angles from the hyphae. Oval, 2-5 mm conidia were formed at the end of the conidiophores giving a flowerlike appearance. In some areas “sleeves” of spores could be found along the hyphae as well. A 37°C culture of this organism produced small, cigar-shaped yeast cells.

This organism is most likely:

A. Histoplasma capsulatum
B. Sporothrix schenckii
C. Blastomyces dermatitidis
D. Candida albicans

Answer 137

B. Sporothrix schenckii

Question 138

The Epstein-Barr virus is associated with which of the following:

A. Chickenpox
B. Hodgkin lymphoma
C. Burkitt lymphoma
D. Smallpox

Answer 138

C. Burkitt lymphoma

Question 139

MODIFIED TRICHROME STAIN FOR MICROSPORIDIA
Specimen:
1.Fresh
2.Refrigerated
3.Fixed with ethanol
4.Fixed with formalin

A. 1 and 3
B. 1 and 4
C. 2 and 3
D. 2 and 4

Answer 139

B. 1 and 4

Question 140

All of the following are appropriate when attempting to isolate N. gonorrhoeae from a genital specimen except:

A. Transport the genital swab in charcoal transport medium
B. Plate the specimen on modified Thayer-Martin (MTM) medium
C. Plate the specimen on New York City or Martin-lewis agar
D. Culture specimens in ambient oxygen at 37C

Answer 140

D. Culture specimens in ambient oxygen at 37C

Question 141

Sensitivity testing commonly required, except:

A. Acinetobacter
B. Enterococci
C. Enterobacteriaceae
D. Listeria monocytogenes

Answer 141

D. Listeria monocytogenes

Question 142

The most common cause for failure of a GasPak anaerobe jar to establish an adequate environment for anaerobic incubation is:

A. Failure of the oxidation-reduction potential indicator system due to deterioration of methylene blue
B. The failure of the packet to generate adequate H2 and/or CO2
C. Condensation of water on the inner surface of the jar
D. Catalysts that have become inactivated after repeated use

Answer 142

D. Catalysts that have become inactivated after repeated use

Question 143

Production of exotoxin A, which kills host cells by inhibiting protein synthesis and production of several proteolytic enzymes and hemolysins that destroy cells and tissue are factors that contribute to pathogenicity of which of the following organisms?

A. Pseudomonas aeruginosa
B. Burkholderia cepacia
C. Ralstonia pickettii
D. Burkholderia mallei

Answer 143

A. Pseudomonas aeruginosa

Question 144

The most critical step in obtaining accurate Gram stain results is the application of which of the following?

A. Safranin
B. Crystal violet
C. Gram’s iodine
D. Acetone/ethanol

Answer 144

D. Acetone/ethanol

Question 145

An anaerobic, box-shaped gram-positive bacillus ispositive for the reverse CAMP test. This organism would also be:

A. Lipase positive
B. Indole positive
C. Lecithinase positive
D. Spore negative

Answer 145

C. Lecithinase positive

Question 146

Which of the following is the correct location of enteric “H” antigens?

A. Flagella
B. Capsule
C. Cell wall
D. Cytoplasm

Answer 146

A. Flagella

Question 147

Which of the following has been recognized in postinfectious complications of a Campylobacter jejuni infection?

A. Guillain-Barré syndrome
B. Chronic pulmonary disease
C. Encephalitis
D. Endocarditis

Answer 147

A. Guillain-Barré syndrome

Question 148

A 2-month-old infant in good health was scheduled for a checkup at the pediatrician’s office. After arriving for the appointment, the mother noted white patches on the baby’s tongue and in his mouth. The baby constantly used a pacifier. What is the most likely organism causing the white patches

A. Cryptococcus neoformans
B. Candida albicans
C. Aspergillus fumigatus
D. None of these options

Answer 148

B. Candida albicans

Question 149

An emergency department physician suspected Corynebacterium diphtheriae when examining the sore throat of an exchange student from South America. What is the appropriate media for the culture of the nasopharyngeal swab obtained from the patient?

A. Chocolate agar
B. Thayer–Martin agar
C. Tinsdale medium
D. MacConkey agar

Answer 149

C. Tinsdale medium

Question 150

A tissue biopsy specimen of the stomach was obtained from a 38-year-old male patient diagnosed with gastric ulcers. The specimen was transported immediately and processed for culture and histology. At 5 days, the culture produced colonies of gram-negative (curved) bacilli on chocolate and Brucella agar with 5% sheep blood. The cultures were held at 35°C–37°C in a microaerophilic atmosphere. The colonies tested positive for urease. The most likely identification is:

A. Escherichia coli
B. Helicobacter pylori
C. Enterococcus faecalis
D. Streptococcus bovis

Answer 150

B. Helicobacter pylori

Question 151

During the summer break, several middle-aged elementary school teachers from the same school district attended a 3-day seminar in Chicago. Upon returning home, three female teachers from the group were hospitalized with pneumonia, flulike symptoms, and a nonproductive cough. Routine testing of sputum samples revealed normal flora. Further testing using buffered CYE agar with L-cysteine and α-ketoglutarate in 5% CO2 produced growth of opaque colonies that stained faintly, showing thin gram-negative rods.

What is the most likely identification?

A. Legionella pneumophila
B. Haemophilus influenzae
C. Eikenella corrodens
D. Streptococcus pneumoniae

Answer 151

A. Legionella pneumophila

Question 152

Anaerobic gram-negative rods were recovered from the blood of a patient after gallbladder surgery. The bacteria grew well on agar containing 20% bile, but were resistant to kanamycin and vancomycin. What is the most likely identification?

A. Clostridium perfringens
B. Bacteroides fragilis group
C. Prevotella spp.
D. Porphyromonas spp.

Answer 152

B. Bacteroides fragilis group

Question 153

“Clue cells” are seen on a smear of vaginal discharge obtained from an 18-year-old female emergency department patient. This finding, along with a fishy odor (amine) after the addition of 10% KOH, suggests bacterial vaginosis caused by which organism?

A. Staphylococcus epidermidis
B. Streptococcus agalactiae
C. Gardnerella vaginalis
D. Escherichia coli

Answer 153

C. Gardnerella vaginalis

Question 154

This antiseptic has been traditionally used to obtain the high degree of skin antisepsis required when BLOOD CULTURES are being collected:

A. 70% Ethyl alcohol
B. 70% Isopropanol
C. Hydrogen peroxide
D. Povidone–iodine

Answer 154

D. Povidone–iodine

Question 155

The indicator employed in TSI agar and urease test medium is:

A. Phenol red
B. Bromcresol purple
C. Bromthymol blue
D. Neutral red

Answer 155

A. Phenol red

Question 156

The composition of optochin sensitivity test disk is:

A. 10% sodium desoxycholate
B. Bacitracin
C. Para-dimethylcinnamaldehyde
D. Ethylhydrocupreine hydrochloride

Answer 156

D. Ethylhydrocupreine hydrochloride

Question 157

Plasma of choice for the coagulase test is:

A. Sheep plasma
B. Human plasma
C. Rabbit plasma
D. Rabbit serum

Answer 157

C. Rabbit plasma

Question 158

After satisfactory performance of daily disk diffusion susceptibility quality control is documented, the frequency of quality control can be reduced to:

A. Twice a week
B. Every week
C. Every other week
D. Every month

Answer 158

B. Every week

Question 159

In disk diffusion susceptibility testing, as an antimicrobial agent diffuses away from the disk, the concentration of antibiotic is:

A. Increased
B. Decreased
C. Unchanged
D. Inoculum dependent

Answer 159

B. Decreased

Question 160

30% exhausted, 70% recirculated:

A. Class I
B. Class II A1
C. Class II B1
D. Class II B2

Answer 160

B. Class II A1

Question 161

Sterile, screw-cap container tube, except:

A. Joint fluid
B. Sputum
C. Urine
D. Wound abscess

Answer 161

D. Wound abscess

Question 162

Which of the following is the most appropriate method for collecting a urine specimen from a patient with an indwelling catheter?

A. Remove the catheter, cut the tip, and submit it for culture
B. Disconnect the catheter from the bag, and collect urine from the terminal end of the catheter
C. Collect urine directly from the bag
D. Aspirate urine aseptically from the catheter tubing

Answer 162

D. Aspirate urine aseptically from the catheter tubing

Question 163

Cerebrospinal fluid (CSF) should be cultured immediately, but if delayed the specimen should be:

A. Refrigerated at 4C to 6C
B. Frozen at -20C
C. Stored at room temperature for no longer than 24 hours
D. Incubated at 37C and cultured as soon as possible

Answer 163

D. Incubated at 37C and cultured as soon as possible

Question 164

Growth in broth, except:

A. Diffuse
B. Flocculent
C. Pellicle
D. Turbid

Answer 164

A. Diffuse

Question 165

Black belts dedicate ____ of their time to quality improvement projects, proactively addressing process and quality problems.

A. 10%
B. 20%
C. 70%
D. 100%

Answer 165

D. 100%

Question 166

Green belts contribute ____ of their time to improvement projects while delivering their normal job functions.

A. 10%
B. 20%
C. 70%
D. 100%

Answer 166

B. 20%

Question 167

Black belts

A. Project sponsors or champions
B. Project coaches or leaders
C. Project team members
D. Not traditionally used

Answer 167

B. Project coaches or leaders

Question 168

Green belts

A. Project sponsors or champions
B. Project coaches or leaders
C. Project team members
D. Not traditionally used

Answer 168

C. Project team members

Question 169

Blue belts

A. Project sponsors or champions
B. Project coaches or leaders
C. Project team members
D. Not traditionally used

Answer 169

A. Project sponsors or champions

Question 170

Biodegradable wastes like leftover food, used cooking oil, fish entrails, scale, fins, fruits, vegetable peelings, rotten fruits, and vegetables:

A. Orange
B. Red
C. Green
D. Black

Answer 170

C. Green

Question 171

Non-biodegradable wastes like paper or paper products (newspaper, tetra packs, etc.), bottles (glass and plastics), and packaging materials (Styropor, candy wrapper, aluminum cans):

A. Orange
B. Red
C. Green
D. Black

Answer 171

D. Black

Question 172

Radioactive wastes or medical equipment contaminated or exposed in radioactivity:

A. Orange
B. Red
C. Green
D. Black

Answer 172

A. Orange

Question 173

Pharmaceutical and chemical wastes:

A. Yellow
B. Yellow with black band
C. Red
D. Orange

Answer 173

B. Yellow with black band

Question 174

Infectious and pathological wastes such as used test strips, used beads or plates, used reaction pads or foils, used swabs, used gloves, used cord clamp, used plaster, used masks:

A. Yellow
B. Yellow with black band
C. Red
D. Orange

Answer 174

A. Yellow

Question 175

Component(s) of the chain of infection:

A. Susceptible host
B. Entry portal
C. Transmission of the pathogen
D. All of these

Answer 175

D. All of these

Question 176

In the Hierarchy of Controls, which of the following is most effective in preventing exposures:

A. Personal protective equipment
B. Substitution of toxic substances
C. Hazard elimination
D. Engineering controls

Answer 176

C. Hazard elimination

Question 177

Use of which of the following is a method of substitution of a work-related hazard:

A. Sharp containers
B. Non-latex gloves instead of latex gloves
C. Patient lift equipment
D. Hand sanitizers

Answer 177

B. Non-latex gloves instead of latex gloves

Question 178

Autonomy is:

A. Providing informed consent
B. Conducting walk-throughs
C. Addressing workplace bullying and violence
D. Not singling out workers/groups for hazardous duties

Answer 178

A. Providing informed consent

Question 179

Classic web-like pellicle is associated with ____________ meningitis and can be seen after overnight refrigeration of the fluid.

A. Bacterial meningitis
B. Fungal meningitis
C. Tubercular meningitis
D. Viral meningitis

Answer 179

C. Tubercular meningitis

Question 180

Severe disseminated intravascular coagulation often complicates cases of septicemia caused by:

A. Acinetobacter sp.
B. Moraxella sp.
C. Neisseria gonorrhoeae
D. Neisseria meningitidis

Answer 180

D. Neisseria meningitidis

Question 181

Small, gray, glistening; colonies tend to dip down in the center and RESEMBLE A DOUGHNUT (umbilicated) as they age; if organism has a polysaccharide capsule, colony may be mucoid; ALPHA-HEMOLYTIC:

A. Streptococcus pyogenes
B. Streptococcus agalactiae
C. Streptococcus pneumoniae
D. Staphylococcus aureus

Answer 181

C. Streptococcus pneumoniae

Question 182

A teenaged boy suffered a foot laceration while swimming in a polluted water area in a river. He did not seek medical treatment, and the wound developed a foul-smelling exudate. One of the bacteria isolated from the abscess exudate was missing superoxide dismutase, catalase, and a peroxidase. Which of the following statements best describes this microorganism?

A. It is a capnophile
B. It is a facultative anaerobe
C. It is a microaerophile
D. It is an anaerobe
E. It is an obligate aerobe

Answer 182

D. It is an anaerobe

Question 183

Which of the following is the correct order of the procedural steps when performing the Gram stain?

A. Fixation, crystal violet, alcohol/acetone decolorization, safranin
B. Fixation, crystal violet, iodine treatment, alcohol/acetone decolorization, safranin
C. Fixation, crystal violet, iodine treatment, safranin
D. Fixation, crystal violet, safranin
E. Fixation, safranin, iodine treatment, alcohol/acetone decolorization, crystal violet

Answer 183

B. Fixation, crystal violet, iodine treatment, alcohol/acetone decolorization, safranin

Question 184

A 78-year-old man presents to the local emergency department with a severe headache and stiff neck. The cerebrospinal fluid (CSF) specimen is cloudy. Analysis reveals 400 white blood cells per cubic millimeter (95% PMNs), a protein concentration of 75 mg/dL, and a glucose concentration of 20 mg/dL. While in the ER, a resident does a Gram stain of the CSF but mistakenly forgets the iodine treatment step. If the meningitis is caused by Streptococcus pneumoniae, how will the bacteria seen on the resident’s slide appear?

A. All the cells will be blue
B. All the cells will be decolorized
C. All the cells will be purple
D. All the cells will be red
E. All the cells will lyse; thus, no Gram stain results will be obtained
F. Half of the cells will be red and the other half will be blue

Answer 184

D. All the cells will be red

Question 185

Several children in a day care center for preschoolers developed fever, irritability, lack of appetite, and a vesicular rash found on their hands, feet, and mouths. With which virus were these children most likely infected?

A. Coronavirus
B. Coxsackievirus A
C. Orthoreovirus
D. Respiratory syncytial virus
E. Rhinovirus

Answer 185

B. Coxsackievirus A

Question 186

A hospital worker is found to be positive for hepatitis B surface antigen. Subsequent tests reveal the presence of HBeAg as well. Which of the following best describes the worker?

A. Has a biologic false-positive test for hepatitis
B. Is highly contagious
C. Is less contagious
D. Is not contagious
E. Has resolved hepatitis B

Answer 186

B. Is highly contagious

Question 187

Which one of the following groups of people is most likely to be at increased risk for HIV infection?

A. Sexual partners of IV drug abusers who share needles
B. Receptionists at a hospital
C. Persons who received blood transfusions in 2013
D. Members of a household in which there is a person who is HIV-positive
E. Factory workers whose coworkers are HIV-positive

Answer 187

A. Sexual partners of IV drug abusers who share needles

Question 188

Subacute sclerosing panencephalitis (SSPE) begins with mild changes in personality, behavior and memory, and seizures. The process is progressive and ends with dementia and death. Infection with which virus precedes SSPE?

A. Epstein–Barr virus
B. HIV
C. JC polyomavirus
D. Measles virus
E. Mumps virus

Answer 188

D. Measles virus

Question 189

An IV-drug user discovered that a friend with whom he shared needles for injections was diagnosed with viral hepatitis. He had his blood drawn at the local public health clinic and tested for HBV. Which of the following markers is usually the first viral marker detected after infection with HBV?

A. HBcAg
B. HBeAg
C. HBsAg
D. HBeAg IgG
E. HBcAg IGM

Answer 189

C. HBsAg

Question 190

An elderly man had been in several military conflicts during the early 1980s and received blood transfusions for injuries. He recently consulted his physician for what was diagnosed as cryoglobulinemia and glomerulonephritis. Additional testing revealed that he was infected by a flavivirus whose transmission was bloodborne. Which of the following viruses was involved in this infection?

A. HAV
B. HBV
C. HCV
D. HDV
E. HEV

Answer 190

C. HCV

Question 191

A scraping from a painful, inflamed wound is found to contain numerous gram-negative bacteria. Upon questioning, the feverish patient states that he was bitten by a cat while trying to rescue it from a storm drain earlier in the day. Given these observations, which of the following organisms is the most likely cause of infection?

A. Aeromonas species
B. Campylobacter jejuni
C. Pasteurella multocida
D. Pseudomonas aeruginosa
E. Yersinia enterocolitica

Answer 191

C. Pasteurella multocida

Question 192

A 25-year-old medical student presents with a ruptured appendix. A peritoneal infection develops, despite prompt removal of the organ and extensive flushing of the peritoneal cavity. An isolate from a pus culture reveals a gram-negative rod identified as Bacteroides fragilis. Anaerobic infection with B. fragilis is best characterized by which of the following?

A. A black exudate in the wound
B. A foul-smelling discharge
C. A heme-pigmented colony formation
D. An exquisite susceptibility to penicillin
E. Severe neurologic symptoms

Answer 192

B. A foul-smelling discharge

Generally, wound exudates smell bad owing to production of organic acids by such anaerobes as B. fragilis.

Question 193

A 1-week-old newborn develops meningitis. Short, gram-positive rods are isolated. History reveals that the mother had eaten unpasteurized cheese from Mexico during pregnancy, and she recalled having a flu-like illness. Which of the following is the most likely etiologic microorganism?

A. Corynebacterium diphtheriae
B. Escherichia coli
C. Group B streptococci
D. Listeria monocytogenes
E. Streptococcus pneumoniae

Answer 193

D. Listeria monocytogenes

Question 194

A patient is hospitalized after an automobile accident. The wounds become infected, and the patient is treated with tobramycin, carbenicillin, and clindamycin. Five days after antibiotic therapy was initiated, the patient develops severe diarrhea and pseudomembranous enterocolitis. Antibiotic-associated diarrhea and the more serious pseudomembranous enterocolitis can be caused by which of the following organisms?

A. Bacteroides fragilis
B. Clostridium difficile
C. Clostridium perfringens
D. Clostridium sordellii
E. Staphylococcus aureus

Answer 194

B. Clostridium difficile

Question 195

A patient complains to his dentist about a draining lesion in his mouth. A Gram stain of the pus shows a few gram-positive cocci, leukocytes, and many-branched gram-positive rods. Branched yellow sulfur granules are observed by a microscope. Which of the following is the most likely cause of the disease?

A. Actinomyces israelii
B. Actinomyces viscosus
C. Corynebacterium diphtheriae
D. Propionibacterium acnes
E. Staphylococcus aureus

Answer 195

A. Actinomyces israelii

Question 196

The minimum concentration of antimicrobial agent needed to prevent visually discernible growth of a bacterial or fungal suspension.

A. Minimum bactericidal concentration (MBC)
B. Minimum inhibitory concentration (MIC)
C. Both of these
D. None of these

Answer 196

B. Minimum inhibitory concentration (MIC)

Question 197

The minimum concentration of antimicrobial agent needed to yield a 99.9% reduction in viable colony-forming units of a bacterial or fungal suspension.

A. Minimum bactericidal concentration (MBC)
B. Minimum inhibitory concentration (MIC)
C. Both of these
D. None of these

Answer 197

A. Minimum bactericidal concentration (MBC)

Question 198

The two cations known to influence the activity of aminoglycosides are:

A. Sodium and potassium
B. Calcium and potassium
C. Calcium and magnesium
D. Sodium and magnesium

Bailey

Answer 198

C. Calcium and magnesium

Question 199

When setting up a urine culture, a calibrated loop is used that delivers a specific amount of urine to the media plate. What is that amount?

A. 0.01 or 0.001 mL of urine
B. 0.10 or 0.01 mL of urine
C. 0.001 or 0.0001 mL of urine
D. None of the above is correct

Bailey

Answer 199

A. 0.01 or 0.001 mL of urine

Most often, microbiologists use a calibrated loop designed to deliver a known volume, either 0.01 or 0.001 mL of urine.
These loops, made of platinum, plastic, or other material, can be obtained from laboratory supply companies.
The calibrated loop that delivers the larger volume of urine (0.01 mL) is recommended to detect lower numbers of organisms in certain specimens.

Question 200

Transmission of Orientia tsutsugamushi is associated with what vector?

A. Ticks
B. Fleas
C. Lice
D. Chiggers

Bailey

Answer 200

D. Chiggers

Question 201

Transcription is:

A. Producing DNA from DNA
B. Producing proteins from RNA
C. Creating chromosomes from DNA and histone proteins
D. Producing RNA from DNA

Bailey

Answer 201

D. Producing RNA from DNA

Question 202

Nonspecific immunity includes all of the following except:

A. Inflammation
B. Phagocytosis by neutrophils
C. B-cell activation to produce antibodies
D. Resident normal flora

Bailey

Answer 202

C. B-cell activation to produce antibodies

Question 203

Most laboratories use which type of fire extinguisher?

A. Type A
B. Type B
C. Type C
D. Combination ABC

Bailey

Answer 203

D. Combination ABC

Question 204

All of the following are differential media except:

A. Blood agar
B. Chocolate agar
C. MacConkey’s agar
D. Eosin methylene blue agar

Bailey

Answer 204

B. Chocolate agar

Question 205

What is the stain that binds to the nucleic acid of organisms but does not discriminate between gram-positive or gram-negative organisms called?

A. Ziehl-Neelsen stain
B. Auramine-rhodamine stain
C. Gram stain
D. Acridine orange stain

Bailey

Answer 205

D. Acridine orange stain

Question 206

Dark-field microscopy is used for the microscopic examination of what types of bacteria?

A. Gram-positive cocci such as Staphylococcus aureus
B. Yeast such as Candida tropicalis
C. Gram-negative bacilli such as Escherichia coli
D. Spirochetes such as Treponema pallidum

Bailey

Answer 206

D. Spirochetes such as Treponema pallidum

Question 207

The complete clearing of media around bacterial colonies on a blood agar plate is referred to as:

A. Alpha hemolysis
B. Beta hemolysis
C. Gamma hemolysis
D. Delta hemolysis

Bailey

Answer 207

B. Beta hemolysis

Question 208

What temperature is used to achieve DNA denaturation to a single strand?

A. 74 °C
B. 92 °C
C. 94 °C
D. 102 °C

Bailey

Answer 208

C. 94 °C

Question 209

The mechanism of action for tetracycline is inhibition of:

A. RNA synthesis
B. Cell wall synthesis
C. Protein synthesis
D. Membrane function

Answer 209

C. Protein synthesis

Question 210

All of the following can be used to detect toxin from C. diphtheriae except:

A. Guinea pig lethality test
B. Elek test
C. Modified Tinsdale
D. PCR

Bailey

Answer 210

C. Modified Tinsdale

Question 211

Which organism exhibits end-over-end tumbling motility when incubated in nutrient broth at room temperature for 1 to 2 hours

A. C. diphtheriae
B. C. jeikeium
C. Arthrobacter sp.
D. L. monocytogenes

Bailey

Answer 211

D. L. monocytogenes

Question 212

Pregnant women and immunocompromised patients should avoid eating which of the following foods to prevent Listeria infection

A. Feta cheese
B. Peanuts
C. Pickles
D. Ice cream

Bailey

Answer 212

A. Feta cheese

Question 213

Infection caused by non–acid-fast aerobic actinomycetes is usually chronic, granulomatous lesions of the skin referred to as:

A. Mycelium
B. Necrosis
C. Impetigo
D. Mycetoma

Bailey

Answer 213

D. Mycetoma

Question 214

Enterobacteriaceae are typically gram negative and:

A. Non–glucose fermenters
B. Capable of reducing nitrates to nitrites
C. Catalase negative
D. Oxidase positive

Bailey

Answer 214

B. Capable of reducing nitrates to nitrites

Question 215

Incubation of which organism at 25°C produces a characteristic yellow pigment?

A. Cronobacter (Enterobacter) sakazakii
B. Plesiomonas shigelloides
C. Enterobacter aerogenes
D. Hafnia alvei

Bailey

Answer 215

A. Cronobacter (Enterobacter) sakazakii

Question 216

A patient presents to the physician with pain and frequency of urination. The urine culture reveals a non–lactose fermenting, gram-negative rod with characteristic swarming on blood agar. The biochemical test that would specifically distinguish this organism from other Enterobacteriaceae is:

A. Lactose fermentation
B. Oxidase
C. Phenylalanine deaminase and H2S
D. Triple sugar iron agar

Bailey

Answer 216

C. Phenylalanine deaminase and H2S

Question 217

Which of the following is the key pathogen that infects the lungs of patients with cystic fibrosis?

A. B. cepacia
B. B. pseudomallei
C. P. fluorescens
D. P. aeruginosa

Bailey

Answer 217

D. P. aeruginosa

Question 218

The most common cause of hemolytic uremic syndrome is:

A. EPEC
B. EAEC
C. O157:NM
D. O157:H7

Bailey

Answer 218

D. O157:H7

Question 219

Which E. coli produces a heat-labile (LT) enterotoxin and a heat-stable enterotoxin?

A. UPEC
B. ETEC
C. MNEC
D. EHEC

Bailey

Answer 219

B. ETEC

Question 220

Which organism has large, smooth, glistening colonies with a lavender pigment and smells like ammonia?

A. Acinetobacter spp.
B. Bordetella spp.
C. Stenotrophomonas sp.
D. Burkholderia sp.

Bailey

Answer 220

C. Stenotrophomonas sp.

Question 221

Which organisms are plump coccobacilli that may resist decolorization and may be mistaken for Neisseria spp?

A. Acinetobacter spp.
B. Bordetella spp.
C. Stenotrophomonas sp.
D. Burkholderia sp.

Bailey

Answer 221

A. Acinetobacter spp.

Question 222

Large, nonpigmented or gray, opaque, smooth; friable “HOCKEY PUCK” consistency; colony may be moved intact over surface of CAP:

A. Neisseria gonorrhoeae
B. Neisseria meningitidis
C. Neisseria elongata
D. Moraxella catarrhalis

Bailey

Answer 222

D. Moraxella catarrhalis

Question 223

Into which genus have Haemophilus aphrophilus and Haemophilus paraphrophilus been recently reclassified?

A. Actinobacillus
B. Aggregatibacter
C. Haemophilus
D. Pasteurella

Bailey

Answer 223

B. Aggregatibacter

Question 224

All of the following organisms require X and V factors, except:

A. H. influenzae
B. H. haemolyticus
C. H. influenzae biotype aegyptius
D. Aggregatibacter aphrophilus

Bailey

Answer 224

D. Aggregatibacter aphrophilus

Question 225

All species of the genus Haemophilus require which of the following for in vitro growth?

A. Nicotine adenine dinucleotide (NAD)
B. Cystine
C. Hemin
D. A and C

Bailey

Answer 225

D. A and C

Question 226

Which of the following Haemophilus species is an agent of a sexually transmitted disease?

A. H. parainfluenzae
B. H. influenzae
C. H. ducreyi
D. H. segnis

Bailey

Answer 226

C. H. ducreyi

Question 227

Which encapsulated type of H. influenzae is most common?

A. Type a
B. Type b
C. Type c
D. Type d

Bailey

Answer 227

B. Type b

Question 228

Campylobacter are:

A. Small, curved, motile, gram-positive bacilli
B. Small, curved, motile gram-negative bacilli
C. Small, curved, nonmotile, gram-negative bacilli
D. Small, curved, nonmotile, gram-negative bacilli

Bailey

Answer 228

B. Small, curved, motile gram-negative bacilli

Question 229

Which of the following has been recognized in postinfectious complications of Campylobacter jejuni infection?

A. Guillain-Barré syndrome
B. Chronic pulmonary disease
C. Encephalitis
D. Endocarditis

Bailey

Answer 229

A. Guillain-Barré syndrome

Question 230

A positive hippurate hydrolysis is a characteristic of:

A. Campylobacter coli
B. Campylobacter jejuni
C. Campylobacter lari
D. Campylobacter fetus

Bailey

Answer 230

B. Campylobacter jejuni

Question 231

Campylobacter species should be grown at what optimum temperature?

A. 25° C
B. 37° C
C. 42° C
D. None of the above

Answer 231

C. 42° C

Question 232

All of the following agars may be used to isolate Helicobacter except:

A. Campy-CVA
B. Skirrow’s
C. Thiosulfate-citrate-bile salts-sucrose agar (TCBS)
D. Modified Thayer-Martin

Bailey

Answer 232

C. Thiosulfate-citrate-bile salts-sucrose agar (TCBS)

Stool specimens submitted for culture of H. cinaedi and H. fennelliae are inoculated onto selective media used for Campylobacter isolation but without cephalothin such as Campy-CVA.
For the recovery of H. pylori from tissue biopsy specimens including gastric antral biopsies, non-selective agar media, including chocolate agar and Brucella agar with 5% sheep blood, have resulted in successful recovery of the organisms.
Selective agar such as Skirrow’s and modified Thayer-Martin agar also support growth.

Question 233

When S. moniliformis is acquired by ingestion, the disease is called:

A. Trench fever
B. Haverhill fever
C. Cat scratch disease
D. Lyme disease

Bailey

Answer 233

B. Haverhill fever

Question 234

Specimen characteristics of an anaerobic infection include:

A. Foul odor, presence of sulfur granules, and green fluorescence
B. Foul odor, presence of metachromatic granules, and green fluorescence
C. Foul odor, sulfur smell, and red fluorescence
D. Foul odor, presence of sulfur granules, and red fluorescence

Bailey

Answer 234

D. Foul odor, presence of sulfur granules, and red fluorescence

Upon receipt in the laboratory, specimens should be inspected for characteristics that strongly indicate the presence of anaerobes:
Foul odor
Sulfur granules (associated with Actinomyces spp., Propionibacterium spp., or Eubacterium nodatum)
Brick red fluorescence under long wavelength ultraviolet (UV) light (associated with pigmented Prevotella or Porphyromonas spp).

Question 235

Bartonella quintana has been known to cause:

A. Carrion’s disease
B. Trench fever
C. Cat-scratch disease
D. Lyme disease

Bailey

Answer 235

B. Trench fever

Question 236

What is the specimen of choice for culturing B. pertussis?

A. Throat
B. NP swab
C. Sputum
D. Anterior nose

Bailey

Answer 236

B. NP swab

Question 237

The natural habitat of Streptobacillus moniliformis is the upper respiratory tract of:

A. African dwarf frogs
B. Wild and laboratory rats
C. Prairie rattlesnakes
D. Black-footed ferrets

Bailey

Answer 237

B. Wild and laboratory rats

Question 238

Sulfur granules in a clinical specimen indicate the presence of:

A. Clostridium spp.
B. Fusobacterium spp.
C. Actinomyces spp.
D. Peptostreptococcus spp.

Bailey

Answer 238

C. Actinomyces spp.

Question 239

In patients who are HIV positive or who have AIDS, chronic pulmonary disease may be associated with infection as a result of:

A. Mycobacterium gordonae
B. Mycobacterium kansasii
C. Mycobacterium avium complex
D. Mycobacterium fortuitum

Bailey

Answer 239

C. Mycobacterium avium complex

Question 240

Which organism causes Rocky Mountain spotted fever?

A. Chlamydia trachomatis
B. Ehrlichia chaffeensis
C. Rickettsia rickettsii
D. Coxiella burnetii

Bailey

Answer 240

C. Rickettsia rickettsii

Question 241

Which of the following organisms is acquired via exposure to infected birds?

A. Coxiella burnetii
B. Chlamydia psittaci
C. Anaplasma phagocytophilum
D. Tropheryma whipplei

Bailey

Answer 241

B. Chlamydia psittaci

Question 242

Which serovar of Chlamydia trachomatis causes lymphogranuloma venereum?

A. A
B. C
C. H
D. L1

Bailey

Answer 242

D. L1

Question 243

Which triad of symptoms is associated with rickettsial infections?

A. Urethral discharge, fever, and dysuria
B. Coughing, production of sputum, and chest pain
C. Fever, headache, and rash
D. Genital lesion, swollen inguinal lymph nodes, and headache

Bailey

Answer 243

C. Fever, headache, and rash

Question 244

Which test can be used to differentiate T. mentagrophytes from T. rubrum?

A. Fluorescence using a Wood’s lamp
B. In vitro hair perforation
C. Red color on reverse side of colony
D. Pyriform microconidia

Bailey

Answer 244

B. In vitro hair perforation

Question 245

Germ tube formation is seen with which two yeasts?

A. C. albicans, C. neoformans
B. C. albicans, C. parapsilosis
C. C. glabrata, C. parapsilosis
D. C. albicans, C. dubliniensis
E. C. glabrata, C. dubliniensis

Bailey

Answer 245

D. C. albicans, C. dubliniensis

Question 246

A nonpigmented mycobacterium is isolated that reduces nitrate to nitrite and is niacin positive. You should suspect:

A. M. kansasii
B. M. xenopi
C. M. tuberculosis
D. M. avium complex (MAC)

Answer 246

C. M. tuberculosis

Question 247

Acid-fast staining of a smear prepared from digested sputum showed slender, slightly curved, beaded, red mycobacterial rods. Growth on Middlebrook 7H10 slants produced buff-colored microcolonies with a SERPENTINE PATTERN after 14 days at 37°C. NIACIN AND NITRATE REDUCTION TESTS WERE POSITIVE. What is the most probable presumptive identification?

A. Mycobacterium tuberculosis
B. Mycobacterium ulcerans
C. Mycobacterium kansasii
D. Mycobacterium avium–intracellulare complex

Answer 247

A. Mycobacterium tuberculosis

Question 248

The genus of virus associated with anogenital warts, cervical dysplasia and neoplasia is:

A. Herpes simplex virus
B. Human papillomavirus
C. Cytomegalovirus
D. Coxsackievirus

Answer 248

B. Human papillomavirus

Question 249

The Epstein-Barr virus is associated with which of the following:

A. Chickenpox
B. Hodgkin lymphoma
C. Burkitt lymphoma
D. Smallpox

Answer 249

C. Burkitt lymphoma

Question 250

Which one of the following viruses is responsible for the most common congenital infection?

A. VZV
B. CMV
C. EBV
D. Adenovirus

Answer 250

B. CMV

Question 251

The best medium for culture of Bordetella pertussis is:

A. Phenylethyl alcohol agar
B. Potassium tellurite blood agar
C. Regan-Lowe agar
D. Tinsdale agar

Answer 251

C. Regan-Lowe agar

Question 252

Anticoagulants acceptable for use with blood, bone marrow and synovial fluid specimens that are to be cultured include:

A. EDTA and sodium citrate
B. Heparin and sodium citrate
C. Sodium polyanethol sulfonate (SPS) and heparin
D. Sodium polyanethol sulfonate (SPS) and EDTA

Answer 252

C. Sodium polyanethol sulfonate (SPS) and heparin

Question 253

Which test can be used to diagnose infection and confirm eradication of Helicobacter pylori?

A. DNase
B. Hippurate hydrolysis
C. String test
D. Urea breath test

Answer 253

D. Urea breath test

Question 254

Preanalytical (preexamination) variables in laboratory testing include:

A. Result accuracy
B. Report delivery to the ordering physician
C. Test turnaround time
D. Specimen acceptability

Answer 254

D. Specimen acceptability

Question 255

Direct examination of the treponemes is most often performed by:

A. Light microscopy
B. Darkfield microscopy
C. VDRL testing
D. RPR testing

Answer 255

B. Darkfield microscopy

Question 256

The filovirus that has a characteristic “shepherd’s hook” morphology when viewed by electron microscopy is:

A. Ebola Zaire virus
B. Ebola Reston virus
C. Ebola Sudan virus
D. Marburg virus

Bailey

Answer 256

D. Marburg virus

Question 257

DIC (disseminated intravascular coagulation) is a complication of bloodstream sepsis and is most often caused by:

A. Gram-negative bacteria
B. CMV
C. Gram-positive bacteria
D. Parasites

Bailey

Answer 257

A. Gram-negative bacteria

Question 258

Loeffler’s agar slant is a special culture medium used to recover which organism?

A. Streptococcus pyogenes
B. Corynebacterium diphtheriae
C. Bordetella pertussis
D. Neisseria meningitidis

Answer 258

B. Corynebacterium diphtheriae

Question 259

When setting up a urine culture, a calibrated loop is used that delivers a specific amount of urine to the media plate. What is that amount?

A. 0.01 or 0.001 mL of urine
B. 0.10 or 0.01 mL of urine
C. 0.001 or 0.0001 mL of urine
D. None of the above is correct

Bailey

Answer 259

A. 0.01 or 0.001 mL of urine

Question 260

Which of the ff. makes Mannitol Salt Agar (MSA) selective?

A. Mannitol
B. Phenol red
C. Neutral red
D. Sodium chloride

Answer 260

D. Sodium chloride

Question 261

The classification of a fire that can be extinguished with water is:

A. Class A
B. Class B
C. Class C
D. Class D

Stras

Answer 261

A. Class A

Question 262

The testing of sample from an outside agency and the comparison of results with participating laboratories is called:

A. External QC
B. Electronic QC
C. Internal QC
D. Proficiency testing

Stras

Answer 262

D. Proficiency testing

Proficiency Testing (External Quality Assessment)
External QA (not External QC)
PT or EQA is the testing of unknown samples received from an outside agency, and provides unbiased validation of the quality of patient test results. The laboratory accuracy is evaluated and compared with other laboratories using the same method of analysis.

Question 263

The NPFA classification symbol contains information on all of the following except:

A. Fire hazards
B. Biohazards
C. Reactivity
D. Health hazards

Stras

Answer 263

B. Biohazards

Question 264

The first thing to do when a fire is discovered is to:

A. Rescue persons in danger
B. Activate the alarm system
C. Close doors to other areas
D. Extinguish the fire if possible

Stras

Answer 264

A. Rescue persons in danger

Question 265

Employees should not work with radioisotopes if they are:

A. Wearing contact lenses
B. Allergic to iodine
C. Sensitive to latex
D. Pregnant

Stras

Answer 265

D. Pregnant

Question 266

Centrifuging an uncapped specimen may produce a biologic hazard in the form of:

A. Vectors
B. Sharps contamination
C. Aerosols
D. Specimen contamination

Stras

Answer 266

C. Aerosols

Question 267

All of the following should be discarded in biohazardous waste containers except:

A. Urine specimen containers
B. Towels used for decontamination
C. Disposable lab coats
D. Blood collection tubes

Stras

Answer 267

A. Urine specimen containers

Question 268

The best way to break the chain of infection is:
A. Hand sanitizing
B. Personal protective equipment
C. Aerosol prevention
D. Decontamination

Stras

Answer 268

A. Hand sanitizing

Question 269

An immunocompromised patient was admitted to the hospital with a diagnosis of hemorrhagic cystitis. Which combination of virus and specimen would be most appropriate to diagnose a viral cause of this disorder?

A. BK virus—urine
B. Human papilloma virus—skin
C. Hepatitis B virus—serum
D. Epstein–Barr virus—serum

Answer 269

A. BK virus—urine

Question 270

This biological safety hood uses an exhaust fan to move air inward through the open front. The air is circulated within the safety hood, passing through a high-efficiency particulate air (HEPA) filter before reaching the environment outside the hood.

A. Class I BSC
B. Class II A1 BSC
C. Class II B1 BSC
D. Class III BSC

Answer 270

A. Class I BSC

Question 271

Which of these specimens is best for the detection of Pneumocystis jiroveci?

A. Bronchoalveolar lavage
B. Vaginal secretions
C. Bronchial washings
D. Amniotic fluid

Answer 271

A. Bronchoalveolar lavage

Question 272

What is the specimen of choice for the initial diagnosis of Pneumocystis jirovecii (carinii) in an immunocompromised patient, such as someone with AIDS?

A. Induced sputum
B. Open-thorax lung biopsy
C. CSF
D. Urine

Answer 272

A. Induced sputum

Question 273

If only a small amount of CSF is obtained, which is the most important procedure to perform first?

A. Cell count
B. Chemistries
C. Immunology
D. Microbiology

Answer 273

D. Microbiology

Question 274

Inoculum size for DISK DIFFUSION susceptibility testing:

A. 1 x 10^4 CFU/mL
B. 1.5 x 10^5 CFU/mL
C. 1.5 x 10^8 CFU/mL
D. 5 x 10^5 CFU/mL

Answer 274

C. 1.5 x 10^8 CFU/mL

Question 275

Inoculum size for AGAR DILUTION susceptibility testing:

A. 1 x 10^4 CFU/spot
B. 1.5 x 10^5 CFU/spot
C. 1.5 x 10^8 CFU/spot
D. 5 x 10^5 CFU/spot

Answer 275

A. 1 x 10^4 CFU/spot

Question 276

Inoculum size for BROTH DILUTION susceptibility testing:

A. 1 x 10^4 CFU/mL
B. 1.5 x 10^5 CFU/mL
C. 1.5 x 10^8 CFU/mL
D. 5 x 10^5 CFU/mL

Answer 276

D. 5 x 10^5 CFU/mL

Question 277

A delta check is a method that:

A. Determines the mean and variance of an instrument
B. Monitors the testing system for precision
C. Monitors patient samples day to day
D. Is determined by each laboratory facility

Answer 277

C. Monitors patient samples day to day

Question 278

The biochemical tests performed on a gram-positive bacillus were consistent with those of Corynebacterium diphtheriae. The MLS should now:

A. Perform a spore stain of the colonies
B. Determine if the isolate is toxigenic by performing an Elek test
C. Perform an agglutination test to confirm the organism’s identity
D. Subculture the organism to Hektoen enteric medium and examine for black colonies

Answer 278

B. Determine if the isolate is toxigenic by performing an Elek test

Question 279

Which of the following bacteria should be consideredimportant pathogens when reading gram-stained smears of soft tissue abscess?

A. Streptococcus pneumoniae
B. Neisseria gonorrhoeae
C. Pseudomonas aeruginosa
D. Staphylococcus aureus

Answer 279

D. Staphylococcus aureus

Question 280

The toxic shock syndrome toxin-1 is an important virulence factor in staphylococcal disease. This toxin is classified into which of the following groups of toxins?

A. Cytolytic toxin
B. Leukocidin
C. Phospholipase
D. Enterotoxin

Answer 280

D. Enterotoxin

Question 281

Bacillus anthracis and Bacillus cereus can be differentiated in the laboratory by a variety of different test results. Which of the following sets of tests best differentiate these two species?

A. Catalase and glucose fermentation
B. Motility and lecithinase production
C. Oxidase and beta-hemolysis on 5% sheep blood agar
D. Motility and beta-hemolysis on 5% sheep blood agar

Answer 281

D. Motility and beta-hemolysis on 5% sheep blood agar

Question 282

Which of the following specimens would be best for identifying Bacillus cereus as the cause of an outbreak of food poisoning?

A. Blood
B. Rectal swabs
C. Stool samples
D. Food

Answer 282

D. Food

Question 283

Differentiation of Stenotrophomonas maltophilia and Burkholderia cepacia is best accomplished by which of the following tests?

A. Oxidase test
B. Maltose and glucose medium
C. Tyrosine-enriched heart infusion agar
D. Growth at 42C

Answer 283

A. Oxidase test

Question 284

Which of the following is the most sensitive method for the diagnosis of Chlamydia trachomatis?

A. Cytology
B. Culture
C. Nucleic acid amplification
D. Serologic testing

Answer 284

C. Nucleic acid amplification

Question 285

The gram-stained smear shows an organism isolated from a blood culture after bowel surgery. Under anaerobic incubation conditions, it grew as smooth, white, nonhemolytic colonies. The organism was not inhibited by colistin, kanamycin, or vancomycin and hydrolyzed esculin. The most likely identification of this isolate is which of the following?

A. Fusobacterium nucleatum
B. Fusobacterium varium
C. Bacteroides fragilis
D. Prevotella melaninogenica

Answer 285

C. Bacteroides fragilis

Question 286

Lecithinase production, double zone hemolysis onsheep blood agar, and gram-stained morphology are all useful criteria in the identification of which of the following?

A. Clostridium perfringens
B. Streptococcus agalactiae
C. Escherichia coli
D. Clostridium tetani

Answer 286

A. Clostridium perfringens

Question 287

In a clinical specimen, the presence of sulfur granules strongly indicates the presence of which anaerobic bacterium?

A. Bacteroides fragilis
B. Actinomyces spp.
C. Fusobacterium nucleatum
D. Clostridium tetani

Answer 287

B. Actinomyces spp.

Question 288

The organism most commonly associated with otitis media infections is associated with which of the following positive test results?

A. Coagulase
B. VP
C. Optochin
D. Bacitracin

Answer 288

C. Optochin

Question 289

The culture of which sample routinely uses quantitation or the counting of bacterial cells present to assist in the interpretation?

A. Blood
B. Sputum
C. Urine
D. Abscess

Answer 289

C. Urine

Question 290

Which of the following is an example of an inappropriate specimen or condition that would warrant rejection for microbiology culture?

A. A nonsterile container for a stool culture
B. A swab of a skin and soft tissue infection
C. A tissue sample for anaerobic culture
D. A 24-hour urine sample for bacteriology culture

Answer 290

D. A 24-hour urine sample for bacteriology culture

Question 291

Which of the following statements best defines “infectious substances”?

A. Articles or substances capable of posing a risk to safety
B. Substances known or reasonably expected to contain pathogens
C. Patient samples containing bacteria
D. Samples with class 3 pathogens

Answer 291

B. Substances known or reasonably expected to contain pathogens

Question 292

Which of the following terms is used to describe an increase of lymphocytes and other mononuclear cells (pleocytosis) in the cerebrospinal fluid and negative bacterial and fungal cultures?

A. Meningoencephalitis
B. Aseptic meningitis
C. Encephalitis
D. Meningitis

Answer 292

B. Aseptic meningitis

Question 293

A college student is examined at the emergency department; he is disoriented with a fever, intense headache, stiff neck, vomiting, and sensitivity to light.
His friends say that he has been sick for about 2 days and that his condition worsened over the last 3 hours. The physician does a complete blood count (CBC) and electrolytes. The electrolytes are normal, but the patient’s white blood count (WBC) is 12,000 cells/L.
What test should the doctor order next?

A. Urine culture
B. Stool culture
C. Cerebrospinal fluid Gram stain and culture
D. Blood culture

Answer 293

C. Cerebrospinal fluid Gram stain and culture

Question 294

Routine culture media for use with a specimen ofcerebrospinal fluid should include which of the following sets of media?

A. 5% sheep blood agar, Lowenstein Jensen agar, 7H9 agar
B. 5% sheep blood agar, thioglycolate broth
C. 5% sheep blood agar, MacConkey agar, Sabourad dextrose agar
D. 5% sheep blood agar, chocolate agar, thioglycolate broth

Answer 294

D. 5% sheep blood agar, chocolate agar, thioglycolate broth

Question 295

In a quality control (QC) procedure on a new batch of Mueller-Hinton plates using a standard QC stock strain of Staphylococcus aureus, the disk inhibition zone sizes for three of the drugs tested were too small and fell below the expected QC range.
Which of the following is the most likely reason for this observation?

A. These three antibiotic disks were outdated and had lost potency
B. These three disks were faulty in that the antibiotic content was too high
C. Bacterial suspension of Staphylococcus was probably contaminated with another organism
D. The plates received insufficient incubation time

Answer 295

A. These three antibiotic disks were outdated and had lost potency

Question 296

A small portion of a colony of a gram-negative bacilli was smeared onto a filter paper test system. One percent tetramethyl-p-phenylenediamine dihydrochloride was added. At 10 seconds, a dark purple color developed where the colony was added to the paper.
Which of the following statements best describes the test results?

A. Positive indole test
B. Positive oxidase test
C. Positive urea test
D. Positive esculin test

Answer 296

B. Positive oxidase test

Question 297

The bacterial isolate on XLD agar shown in the image was isolated from a routine stool culture. Which of the following genera and species is the most likely identification for this organism?

A. Klebsiella pneumoniae
B. Salmonella enteritidis
C. Shigella sonnei
D. Serratia marcescens

Answer 297

B. Salmonella enteritidis

Question 298

In the test for urease production, the presence of the enzyme hydrolyzes urea to which of the following?

A. Ammonia and CO2
B. Putrescine
C. Amines and CO2
D. Amines and water

Answer 298

A. Ammonia and CO2

Question 299

The Runyon system of classification is based on which of the following?

A. Colony and microscopic morphology
B. Biochemical characteristics
C. Growth rate and colonial pigmentation
D. All of the above are correct

Answer 299

C. Growth rate and colonial pigmentation

Question 300

Which of the following tests is important as a part of the genus identification or as part of a preliminary identification but is not used as a confirmatory identification of Bacillus anthracis?

A. Demonstration of a capsule
B. Demonstration of spore formation
C. Positive PCR test
D. Lysis of the strain by specific bacteriophages

Answer 300

B. Demonstration of spore formation

Question 301

Which of the following tests is important as a part of the genus identification or as part of a preliminary identification but is not used as a confirmatory identification of Bacillus anthracis?

A. Demonstration of a capsule
B. Demonstration of spore formation
C. Positive PCR test
D. Lysis of the strain by specific bacteriophages

Answer 301

B. Demonstration of spore formation

Question 302

The bacterial species that can be described as:
Susceptible to penicillin and bacitracin
Beta-hemolytic
A major cause of bacterial pharyngitis
Often carrying an antiphagocytic M protein

A. Enterococcus faecalis
B. Streptococcus pyogenes
C. Streptococcus agalactiae
D. Viridans streptococci

Answer 302

B. Streptococcus pyogenes

Question 303

Within 5 hours of returning home from lunch at your most favorite fast food restaurant you feel very sick and are vomiting.
Which of the following is the most likely causative organism?

A. Staphylococcus aureus
B. Vibrio parahaemolyticus
C. Shigella sonnei
D. Escherichia coli

Answer 303

A. Staphylococcus aureus

Question 304

Production of exotoxin A, which kills host cells by inhibiting protein synthesis and production of several proteolytic enzymes and hemolysins that destroy cells and tissue are factors that contribute to pathogenicity of which of the following organisms?

A. Pseudomonas aeruginosa
B. Burkholderia cepacia
C. Ralstonia pickettii
D. Burkholderia mallei

Answer 304

A. Pseudomonas aeruginosa

Question 305

Which of the following is a disinfectant?

A. Benzalkonium chloride
B. Chlorhexidine gluconate
C. Household bleach
D. Hydrogen peroxide

Answer 305

C. Household bleach

Question 306

In the NAL-C-NaOH method for liquefaction and decontamination of specimens, NaOH acts as a decontaminating agent and as a/an:

a. Liquifying agent
b. Mordant
c. Emulsifier
d. Stabilizing agent

Answer 306

c. Emulsifier

Question 307

Which of the following can specifically grow staphylococci?

1. PEA
2. Columbia CNA
3. MSA
4. BHI

a. 1,2,3,4
b. 1,2,3
c. 2,3,4
d. 1,3,4

Answer 307

a. 1,2,3,4

Question 308

B-naphthylamine is the end product for which of the following Biochemical tests?

a. VP
b. Indole
c. PYR
d. Urease

Answer 308

d. Urease

Question 309

Which of the following PCR tec. uses short primers that are not specifically complementary to a particular sequence of a target DNA?

a. qPCR
b. Nested PCR
c. Multiplex PCR
d. Arbitrary primer PCR

Answer 309

d. Arbitrary primer PCR

Question 310

Which of the following is incorrect regarding the test results for X and V factor test?

a. Haemophilus influenzae will show a halo of growth around the XV disk; the rest of the agar surface will show no growth.
b. Haemophilus parainfluenzae will show a halo of growth around the XV and V disks.
c. Haemophilus aphrophilus will grow over the entire surface of the plate. X and V factors are required for growth.
d. None of these

Answer 310

c. Haemophilus aphrophilus will grow over the entire surface of the plate. X and V factors are required for growth.

Question 311

The release of virions for influenza viruses is through ____

a. binary fission
b. budding
c. multiple fission
d. comp. cell destruction

Answer 311

c. multiple fission

Question 312

Cells are usually large, double refractile when present; buds usually single; however, several may remain attached to parent cells; buds connected by a broad base.

a. M. furfur
b. H. capsulatum
c. B. dermatidis
d. C. immitis

Answer 312

b. H. capsulatum

Question 313

What is the best stain for the sheath of Loa loa microfilariae?

a. Giemsa
b. Grunwald GIemsa
c. Delafield
d. Methylene blue

Answer 313

b. Grunwald GIemsa

Question 314

Which is correct antimicrobial screening plate test for S. epidermidis?

a. Taxo A & FX resistant
b. Taxo A & FX susceptible
c. Taxo A resistant & FX susceptible
d. Taxo A susceptible & FX resistant

Answer 314

d. Taxo A susceptible & FX resistant

Question 315

Gram-negative diplococci was isolated on BAP at 25C. Positive for utilization of glucose and maltose:

a. N. gonorrhoeae
b. N. meningitidis
c. N. subflava
d. M. catarrhalis

Answer 315

c. N. subflava

Question 316

Produces toxin except:

a. Neisseria
b. Clostridium
c. Escherichia
d. Salmonella

Answer 316

a. Neisseria

a. Neisseria - gram neg, no exotoxin
b. Clostridium - gram pos, w/ exotoxin
c. Escherichia - gram neg, w/ exotoxin
d. Salmonella - gram neg, w/ exotoxin

all gram neg have endotoxin (are not produced)
so check exotoxin

Question 317

Outbreak of food poisoning leads to diarrhea in multiple patients. What should be done to investigate the cause of the outbreak?

Answer 317

Phage typing - detection of a single strain of bacteria

Question 318

What is the purpose of flaming wired loops?

a. To prevent cross contamination
b. To sterilize

Answer 318

b. To sterilize

Priority: to avoid over inoculation

Question 319

A specimen positive for Hepatitis A virus spilled. What is the proper disinfectant?

a. Quaternary ammonium compound
b. 90% ethanol
c. Soap and water
d. Hypochlorite

Answer 319

d. Hypochlorite

Question 320

Amoeba that can survive harsh environments like chlorinated water but is killed at 70C

Answer 320

Naegleria fowleri and Acanthamoeba

Both Naegleri and Acanthamoeba can survive hot temperatures up to 60-65C

Question 321

Sealed bucket centrifuge containing liquid culture media should be unloaded in:

a. Fume hood
b. Biosafety cabinet
c. Disinfected bench tops
d. Standard bench tops

Answer 321

b. Biosafety cabinet

Question 322

CSF

a. centrifuge
b. sediment
c. stain
d. culture

Answer 322

a. centrifuge

since this is the first thing to do

Question 323

acceptable specimens for gonorrhea?
I. eye swabs
II. Throat swab
III. Rectal swab
IV. Gastric aspirate

a. I, II, III
b. I, II, III, IV
c. I, II
d. I, III

Answer 323

b. I, II, III, IV

Gastric aspirate - best specimen for infants

Question 324

Nutritive media

a. MAC
b. CNA
c. Thioglycollate broth
d. BAP/CAP

Answer 324

d. BAP/CAP

Question 325

Centrifugation for urine microscopic examination:

A. RCF of 100 for 2 minutes
B. RCF of 400 for 5 minutes
C. RCF of 500 for 5 minutes
D. RCF of 500 for 10 minutes

Answer 325

B. RCF of 400 for 5 minutes

Question 326

The most important diagnostic tool in treating patients with clinical infections in the emergency department:

A. AFB stain
B. Culture
C. Gram stain
D. IMVic reaction

Answer 326

C. Gram stain

Question 327

What is the stain that binds to the nucleic acid of organisms but does not discriminate between gram-positive or gram-negative organisms called?

A. Ziehl-Neelsen stain
B. Auramine-rhodamine stain
C. Gram stain
D. Acridine orange stain

Answer 327

D. Acridine orange stain

Question 328

ANAEROBES usually cannot grow in the presence of O2, and the atmosphere in anaerobe jars, bags, or chambers is composed of:

A. 5% to 10% H2, 5% to 10% CO2, 80% to 90% O2, and 0% N2
B. 5% to 10% H2, 5% to 10% CO2, 80% to 90% N2, and 0% O2
C. 5% to 10% N2, 5% to 10% CO2, 80% to 90% H2, and 0% O2
D. 5% to 10% H2, 5% to 10% N2, 80% to 90% CO2, and 0% O2

Answer 328

B. 5% to 10% H2, 5% to 10% CO2, 80% to 90% N2, and 0% O2

Question 329

McFarland turbidity standard is prepared by mixing _________ to obtain a solution with a specific optical density.

A. 1% hydrochloric acid and 1.175% barium chloride
B. 2% hydrochoric acid and 2.175% barium chloride
C. 1% sulfuric acid and 1.175% barium chloride
D. 2% sulfuric acid and 2.175% barium chloride

Answer 329

C. 1% sulfuric acid and 1.175% barium chloride

Question 330

A suspension of the test organism for use in broth dilution and disk diffusion testing is adjusted to match the turbidity of a:

A. #0.5 McFarland standard
B. #1.0 McFarland standard
C. #2.0 McFarland standard
D. #3.0 McFarland standard

Answer 330

A. #0.5 McFarland standard

Question 331

Unopened, sliced BACON, packaged in material somewhat highly resistant to oxygen permeability, is spoiled mostly by

A. Lactobacilli
B. Micrococci
C. Fecal Streptococci
D. Molds

Answer 331

A. Lactobacilli

Question 332

SAFEST method to ensure that NO INFECTIVE MATERIALS REMAIN in samples or containers when disposed:

A. Autoclave
B. Incineration
C. Pasteurization
D. Filtration

Answer 332

B. Incineration

Question 333

The minimum concentration of antimicrobial agent needed to prevent visually discernible growth of a bacterial or fungal suspension.

A. Minimum bactericidal concentration (MBC)
B. Minimum inhibitory concentration (MIC)
C. Both of these
D. None of these

Answer 333

B. Minimum inhibitory concentration (MIC)

Question 334

The minimum concentration of antimicrobial agent needed to yield a 99.9% reduction in viable colony-forming units of a bacterial or fungal suspension.

A. Minimum bactericidal concentration (MBC)
B. Minimum inhibitory concentration (MIC)
C. Both of these
D. None of these

Answer 334

A. Minimum bactericidal concentration (MBC)

Question 335

pH indicator incorporated in xylose-lysine-desoxycholate (XLD) agar:

A. Bromcresol purple
B. Bromthymol blue
C. Neutral red
D. Phenol red

Answer 335

D. Phenol red

Question 336

A gram-positive coccus recovered from a wound ulcer from a 31-year-old diabetic patient showed pale yellow, creamy, β-hemolytic colonies on blood agar. Given the following test results, what is the most likely identification?
Catalase = +
Glucose OF: positive open tube, negative sealed tube
Mannitol salt = Neg
Slide coagulase = Neg

A. Staphylococcus aureus
B. Staphylococcus epidermidis
C. Micrococcus spp.
D. Streptococcus spp.

Answer 336

C. Micrococcus spp.

Question 337

A light yellow colony from a skin lesion grew aerobically and tested as catalase positive and coagulase negative. The organism gram stained as positive cocci in clusters. The organism was modified oxidase positive, bacitracin susceptible and resistant to lysostaphin. What is the identification of this organism?

A. Staphylococcus aureus
B. Micrococcus luteus
C. Staphylococcus epidermidis
D. Peptostreptococcus anaerobius

Answer 337

B. Micrococcus luteus

Question 338

GRAM + COCCI IN CLUSTERS BUT CATALASE NEGATIVE
A catalase-negative, gram-positive coccus resembling staphylococci (clusters on the Gram- stained smear) was recovered from three different blood cultures obtained from a 60-year-old patient diagnosed with endocarditis. The following test results were noted:
PYR = Neg
Esculin hydrolysis = Neg
Vancomycin = Sensitive
LAP = Neg (V)
6.5% Salt broth = Neg
CAMP test = Neg

What is the correct identification?

A. Leuconostoc spp.
B. Gemella spp.
C. Enterococcus spp.
D. Micrococcus spp.

Answer 338

B. Gemella spp.

Question 339

Access to the laboratory is limited or restricted, and there must be a biohazard sign posted at the entrance of the laboratory:

A. BSL-1
B. BSL-2
C. BSL-3
D. BSL-4

Answer 339

A. BSL-1

Question 340

Access to the laboratory is limited when work is being conducted. The laboratory director is ultimately responsible for determining who may enter or work in the laboratory.

A. BSL-1
B. BSL-2
C. BSL-3
D. BSL-4

Answer 340

B. BSL-2

Question 341

Laboratory should be separated from the other parts of the building and be accessed through two self-closing doors. An ANTEROOM may be used for access.

A. BSL-1
B. BSL-2
C. BSL-3
D. BSL-4

Answer 341

C. BSL-3

Question 342

The BSL facility either is located in a separate building or is in an isolated zone within a building.

A. BSL-1
B. BSL-2
C. BSL-3
D. BSL-4

Answer 342

D. BSL-4

Question 343

Seventy (70) percent recirculated to the cabinet work area through HEPA; 30% balance can be exhausted through HEPA back into the room or to outside through a canopy unit:

A. BSC Class I
B. BSC Class II, A1
C. BSC Class II, B1
D. BSC Class II, B2

Answer 343

B. BSC Class II, A1

Question 344

Thirty (30) percent recirculated, 70% exhausted. Exhaust cabinet air must pass through a dedicated duct to the outside through a HEPA filter.

A. BSC Class I
B. BSC Class II, A1
C. BSC Class II, B1
D. BSC Class II, B2

Answer 344

C. BSC Class II, B1

Question 345

No recirculation; total exhaust to the outside through a HEPA filter.

A. BSC Class I
B. BSC Class II, A1
C. BSC Class II, B1
D. BSC Class II, B2

Answer 345

D. BSC Class II, B2

Question 346

An isolate of Staphylococcus aureus was cultured from an ulcer obtained from the leg of a diabetic 79-year-old female patient. The organism showed resistance to methicillin. Additionally, this isolate should be tested for resistance or susceptibility to:

A. Erythromycin
B. Gentamicin
C. Vancomycin
D. Kanamycin

Answer 346

C. Vancomycin

Question 347

REFER TO BAILEYS
Staphylococcus aureus toxin which disrupts the smooth muscle in blood vessels and is toxic to erythrocytes, leukocytes, hepatocytes, and platelets:

A. Alpha toxin
B. Beta toxin
C. Delta toxin
D. Gamma toxin

Answer 347

A. Alpha toxin

Question 348

Which test is used for the determination of inducible clindamycin resistance in staphylococci and streptococci?

A. E-test
B. D-zone test
C. A-test
D. CAMP test

Answer 348

B. D-zone test

Question 349

The D-zone susceptibility test is used to test inducible resistance on S. aureus strains demonstrating an initial antibiotic susceptibility profile of:

A. Erythromycin sensitive, clindamycin sensitive
B. Erythromycin resistant, clindamycin sensitive
C. Erythromycin resistant, clindamycin resistant
D. Erythromycin sensitive, clindamycin resistant

Answer 349

B. Erythromycin resistant, clindamycin sensitive

Question 350

Resistance to clindamycin can be induced in vitro by

A. Ampicillin
B. Erythromycin
C. Gentamicin
D. Penicillin

Answer 350

B. Erythromycin

Question 351

Which Brucella species may require CO2 for growth, is urea positive in 2 hours, and is inhibited by thionine dye?

A. Brucella abortus
B. Brucella melitensis
C. Brucella suis
D. Brucella canis

Answer 351

A. Brucella abortus

Question 352

Brucella isolate that does not produce H2S, does not require CO2, and is not inhibited by thionine and basic fuchsin is probably which species of Brucella?

A. Brucella canis
B. Brucella abortus
C. Brucella suis
D. Brucella melitensis

Answer 352

D. Brucella melitensis

Question 353

Added to SDA to inhibit most contaminating bacteria:

A. Dextrose
B. Chloramphenicol
C. Cycloheximide
D. Nystatin

Answer 353

B. Chloramphenicol

Question 354

Added to SDA to inhibit saprophytic fungi:

A. Dextrose
B. Chloramphenicol
C. Cycloheximide
D. Nystatin

Answer 354

C. Cycloheximide

Question 355

PROGRESSIVE ENDOPHTHALMITIS
It is a serious pathogen of the eye, causing progressive endophthalmitis:

A. Bacillus anthracis
B. Bacillus cereus
C. Bacillus subtilis
D. Bacillus thurigiensis

Answer 355

B. Bacillus cereus

Question 356

Fluorescence on Wood’s lamp, growth in rice medium:

A. Microsporum canis
B. Microsporum gypseum
C. Microsporum audouinii
D. Epidermophyton floccosum

Answer 356

A. Microsporum canis

Question 357

Fluorescence on Wood’s lamp, no growth in rice medium:

A. Microsporum canis
B. Microsporum gypseum
C. Microsporum audouinii
D. Epidermophyton floccosum

Answer 357

C. Microsporum audouinii

Question 358

Which is the most appropriate nonselective medium for recovery of mycobacteria from a heavily contaminated specimen?

A. Löwenstein–Jensen agar
B. Middlebrook 7H10 agar
C. Petragnani’s agar
D. American Thoracic Society medium

Answer 358

C. Petragnani’s agar

Question 359

Culture media for Vibrio spp., EXCEPT:

A. Buffered glycerol saline
B. Cary-Blair
C. Alkaline peptone water
D. Thiosulfate citrate bile salt (TCBS) agar

Answer 359

A. Buffered glycerol saline

Question 360

Inoculum size for DISK DIFFUSION susceptibility testing:

A. 1 x 10^4 CFU/mL
B. 1.5 x 10^5 CFU/mL
C. 1.5 x 10^8 CFU/mL
D. 5 x 10^5 CFU/mL

Answer 360

C. 1.5 x 10^8 CFU/mL

Question 361

Inoculum size for AGAR DILUTION susceptibility testing:

A. 1 x 10^4 CFU/spot
B. 1.5 x 10^5 CFU/spot
C. 1.5 x 10^8 CFU/spot
D. 5 x 10^5 CFU/spot

Answer 361

A. 1 x 10^4 CFU/spot

Question 362

Inoculum size for BROTH DILUTION susceptibility testing:

A. 1 x 10^4 CFU/mL
B. 1.5 x 10^5 CFU/mL
C. 1.5 x 10^8 CFU/mL
D. 5 x 10^5 CFU/mL

Answer 362

D. 5 x 10^5 CFU/mL

Question 363

What is the number of bacteria needed to cause turbidity in broth culture and to be seen with an unaided eye?

A. 10^2 organisms
B. 10^4 organisms
C. 10^6 organisms
D. 10^8 organisms

Answer 363

C. 10^6 organisms

Question 364

When examining fluids by direct microscopic examination, if one organism is seen per oil immersion field, how many organisms per milliliter of specimen are present?

A. 5^5
B. 7^5
C. 15^5
D. 10^5

Answer 364

D. 10^5

In broth media, nutrients are dissolved in water, and bacterial growth is indicated by a change in the broth’s appearance from clear to turbid (i.e., cloudy). The turbidity, or cloudiness, of the broth is due to light deflected by bacteria present in the culture. More growth indicates a higher cell density and greater turbidity. At least 10^6 bacteria per milliliter of broth are needed for turbidity to be detected with the unaided eye.

All fluids should be processed for direct microscopic examination. In general, if one organism is seen per oil immersion field, at least 10^5 organisms per milliliter of specimen are present. In such cases, often only a few organisms are present in normally sterile body fluids. Therefore, organisms must be concentrated in body fluids.

A minimum concentration of at least 10^5 organisms per milliliter of specimen is required for visualization by light microscopy, whereas by fluorescent microscopy that number decreases to 10^4 per milliliter.

Question 365

An ammonia-like odor is characteristically associated with urine from patients with:

A. Phenylketonuria
B. Viral hepatitis
C. Bacterial infection
D. Yeast infection

Answer 365

C. Bacterial infection

Question 366

The organism most commonly associated with otitis media infections is associated with which of the following positive test results?

A. Coagulase
B. VP
C. Optochin
D. Bacitracin

Answer 366

C. Optochin

Question 367

The optimal collection of a wound specimen for culture of anaerobic organisms is a:

A. Swab of lesion obtained before administration of antibiotics
B. Swab of lesion obtained after administration of antibiotics
C. Syringe filled with pus, obtained before administration of antibiotics
D. Syringe filled with pus, obtained after administration of antibiotics

Answer 367

C. Syringe filled with pus, obtained before administration of antibiotics

Question 368

An organism that must be incubated in a microaerophilic environment for optimal recovery is:

A. Campylobacter jejuni
B. Escherichia coli
C. Pseudomonas aeruginosa
D. Proteus mirabilis

Answer 368

A. Campylobacter jejuni

Question 369

A 21-year-old patient presents with pharyngitis. A throat swab is collected and submitted for anaerobic culture. This specimen should be:

A. Set up immediately
B. Rejected as unacceptable
C. Inoculated into thioglycolate broth
D. Sent to a reference laboratory

Answer 369

B. Rejected as unacceptable

Question 370

Which of the following can be mistaken as myelin globules in sputum?

a. Blastomyces
b. Cryptococcus
c. Histoplasma
d. Candida

Answer 370

a. Blastomyces

Question 371

Which of the following may resemble lymphocytes in CSF?

a. Blastomyces
b. Cryptococcus
c. Histoplasma
d. Candida

Answer 371

b. Cryptococcus

Question 372

Larva in sputum:

a. Ascaris
b. Paragonimus
c. Both of these
d. None of these

Answer 372

a. Ascaris

ASH - larva
Paragonimus - egg in sputum

Question 373

Ova (eggs) in sputum:

a. Ascaris
b. Paragonimus
c. Both of these
d. None of these

Answer 373

b. Paragonimus

ASH - larva in sputum

Question 374

An opportunistic pathogen which possess exotoxin A and is associated with respiratory tract infections of patients with cystic fibrosis

a. Pseudomonas
b. Sterotrophomonas
c. Burkholderia
d. Acinetobacter

Answer 374

a. Pseudomonas

Question 375

Antimicrobial susceptibility testing of anaerobes is done by which of the following methods?

A. Broth disk elution
B. Disk agar diffusion
C. Microtube broth dilution
D. β-Lactamase testing

Answer 375

C. Microtube broth dilution

Question 376

Antimicrobial susceptibility testing of Bacteroides and Clostridium sp. anaerobes are done by which of the following methods?

A. Broth microdilution
B. Agar dilution
C. E-test
D. All of the above

Answer 376

D. All of the above

Question 377

Which of the following is the specimen of choice for detecting rotavirus?

A. Throat swab
B. Urine sample
C. Bronchoalveolar wash
D. Feces sample

Answer 377

D. Feces sample

Question 378

Trophozoite forms of amoebae are found in what type of stool specimen?

A. Formed
B. Loose
C. Soft
D. Watery

Answer 378

D. Watery

Question 379

More likely to contain trophozoites:

A. Liquid/diarrheic stool
B. Formed stool
C. Soft stool
D. None of these

Answer 379

A. Liquid/diarrheic stool

Question 380

May contain trophozoites and cysts:

A. Liquid stool
B. Diarrheic stool
C. Formed stool
D. Soft stool

Answer 380

D. Soft stool

Question 381

More likely to contain cysts (less likely to contain trophozoites)

A. Liquid stool
B. Diarrheic stool
C. Formed stool
D. Soft stool

Answer 381

C. Formed stool

Question 382

Ova recovered from the stool are routinely used to diagnose infections caused by all of the following except?

A. Necator americanus
B. Ascaris lubricoides
C. Trichuris trichiura
D. Strongyloides stercoralis

Answer 382

D. Strongyloides stercoralis

Question 383

Necator americanus rhabditiform larvae can be differentiated from Strongyloides stercoralis rhabditiform larvae by:

A. Length of the notched tail
B. Length of the head region
C. Segmentation
D. Size of the genital primordium

Answer 383

D. Size of the genital primordium

Question 384

This diagnostic stage of Strongyloides stercoralis is best seen in stool using fecal concentration techniques:

A. Eggs
B. Rhabditiform larvae
C. Filariform larvae
D. Adult worms

Answer 384

B. Rhabditiform larvae

Question 385

Infective stage is the SHEATHED FILARIFORM LARVA:

A. Strongyloides stercoralis
B. Ancylostoma duodenale, Necator americanus
C. Ascaris lumbricoides
D. Enterobius vermicularis

Answer 385

B. Ancylostoma duodenale, Necator americanus

Question 386

Infective stage is the UNSHEATHED FILARIFORM LARVA:

A. Strongyloides stercoralis
B. Ancylostoma duodenale, Necator americanus
C. Ascaris lumbricoides
D. Enterobius vermicularis

Answer 386

A. Strongyloides stercoralis

Question 387

Rhabditiform larva with hourglass-shaped esophagus and short buccal cavity:

A. Ascaris
B. Enterobius
C. Necator
D. Strongyloides

Answer 387

D. Strongyloides

Question 388

The rhabditiform larva of the hookworm has a:

A. Long buccal cavity, prominent genital primordium
B. Long buccal cavity, small genital primordium
C. Short buccal cavity, prominent genital primordium
D. Short buccal cavity, small genital primordium

Answer 388

B. Long buccal cavity, small genital primordium

Question 389

The rhabditiform larva of the threadworm has a:

A. Long buccal cavity, prominent genital primordium
B. Long buccal cavity, small genital primordium
C. Short buccal cavity, prominent genital primordium
D. Short buccal cavity, small genital primordium

Answer 389

C. Short buccal cavity, prominent genital primordium

Question 390

Roundworm that inhabits the small intestines and usually demonstrated as rhabditiform larva in stool:

A. A. lumbricoides
B. N. americanus
C. T. spiralis
D. S. stercoralis

Answer 390

D. S. stercoralis

Question 391

The BAERMANN TECHNIQUE yields a good concentration of the living larvae of:

A. Angiostrongylus cantonensis
B. Brugia malayi
C. Enterobius vermicularis
D. Strongyloides stercoralis

Answer 391

D. Strongyloides stercoralis

Question 392

Similar to hookworm eggs:

A. Ascaris
B. Trichuris
C. Trichostrongylus
D. Enterobius

Answer 392

C. Trichostrongylus

Question 393

INTESTINAL NEMATODES
SMALL INTESTINES (CASH)

Answer 393

Capillaria
Ascaris
Strongyloides
Hookworms
& T.spiralis adult

Question 394

INTESTINAL NEMATODES
LARGE INTESTINES (ET)

Answer 394

Enterobius
Trichuris

Question 395

Charcot–Leyden crystals in stool may be associated with an immune response and are thought to be formed from the breakdown products of:

A. Neutrophil
B. Eosinophils
C. Monocytes
D. Lymphocytes

Answer 395

B. Eosinophils

Question 396

Which of the following is the best technique to identify Dientamoeba fragilis in stool?

A. Formalin concentrate
B. Trichrome-stained smear
C. Modified acid-fast–stained smear
D. Giemsa’s stain

Answer 396

B. Trichrome-stained smear

Question 397

An Entamoeba histolytica trophozoite has the following characteristics:

A. Central karyosome in the nucleus, ingestedRBCs, and clear pseudopodia
B. Ingested RBCs, clear pseudopodia, and unevenchromatin on the nuclear membrane
C. Ingested RBCs, clear pseudopodia, and largeglycogen vacuoles in cytoplasm
D. Large, blotlike karyosome, ingested white blood cells (WBCs), and granular pseudopods

Answer 397

A. Central karyosome in the nucleus, ingestedRBCs, and clear pseudopodia

Question 398

Characteristics of the rhabditiform (noninfective) larvae of Strongyloides stercoralis include a:

A. Short buccal capsule and large genital primordium
B. Long buccal capsule and pointed tail
C. Short buccal capsule and small genital primordium
D. Small genital primordium and notch in tail

Answer 398

A. Short buccal capsule and large genital primordium

Question 399

Eating poorly cooked pork can lead to an infection with:

A. Taenia solium and Trichinella spiralis
B. Taenia saginata and Hymenolepis nana
C. Trichuris trichiura and Hymenolepis diminuta
D. Diphyllobothrium latum and Ascaris lumbricoides

Answer 399

A. Taenia solium and Trichinella spiralis

Question 400

An operculated cestode egg that can be recovered from human feces is:

A. Clonorchis sinensis
B. Diphyllobothrium latum
C. Paragonimus westermani
D. Dipylidium caninum

Answer 400

B. Diphyllobothrium latum

Question 401

In infections with Taenia solium, humans can serve as the:

A. Definitive host
B. Intermediate host
C. Either the definitive or the intermediate host
D. None of these options

Answer 401

C. Either the definitive or the intermediate host

Question 402

Oocysts of Cryptosporidium spp. can be detected in stool specimens using:

A. Modified Ziehl–Neelsen acid-fast stain
B. Gram stain
C. Methenamine silver stain
D. Trichrome stain

Answer 402

A. Modified Ziehl–Neelsen acid-fast stain

Question 403

Organisms that should be considered in a waterborne outbreak of diarrheal disease include:

A. Giardia lamblia and Cryptosporidium spp.
B. Endolimax nana and Entamoeba histolytica
C. Blastocystis hominis and Trichomonas vaginalis
D. Toxoplasma gondii and Schistosoma mansoni

Answer 403

A. Giardia lamblia and Cryptosporidium spp.

Question 404

Eye infections with Acanthamoeba spp. have most commonly been traced to:

A. Use of soft contact lenses
B. Use of hard contact lenses
C. Use of contaminated lens care solutions
D. Failure to remove lenses while swimming

Answer 404

C. Use of contaminated lens care solutions

Question 405

Ingestion of which of the following EGGS will result in infection?

A. Strongyloides stercoralis
B. Schistosoma japonicum
C. Toxocara canis
D. Opisthorchis sinensis

Answer 405

C. Toxocara canis

Question 406

Autofluorescence requires no stain and is recommended for the identification of:

A. Entamoeba histolytica cysts
B. Toxoplasma gondii tachyzoites
C. Dientamoeba fragilis trophozoites
D. Cyclospora cayetanensis oocysts

Answer 406

D. Cyclospora cayetanensis oocysts

Question 407

Microsporidial infections can be confirmed using:

A. Light microscopy and modified trichrome stains
B. Phase contrast microscopy and routine trichrome stains
C. Electron microscopy and modified acid-faststains
D. Fluorescence microscopy and hematoxylin stains

Answer 407

A. Light microscopy and modified trichrome stains

Question 408

All of the following are differential media except:

A. Blood agar
B. Chocolate agar
C. MacConkey’s agar
D. Eosin methylene blue agar

Answer 408

B. Chocolate agar

Question 409

What is the stain that binds to the nucleic acid of organisms but does not discriminate between gram-positive or gram-negative organisms called?

A. Ziehl-Neelsen stain
B. Auramine-rhodamine stain
C. Gram stain
D. Acridine orange stain

Answer 409

D. Acridine orange stain

Question 410

Which type of enrichment media is used to isolate Neisseria and Haemophilus organisms?

A. Hektoen enteric (HE) agar
B. Todd Hewitt broth
C. Regan Lowe agar
D. Chocolate agar

Answer 410

D. Chocolate agar

Question 411

The complete clearing of media around bacterial colonies on a blood agar plate is referred to as:

A. Alpha hemolysis
B. Beta hemolysis
C. Gamma hemolysis
D. Delta hemolysis

Answer 411

B. Beta hemolysis

Question 412

The two cations known to influence the activity of aminoglycosides are:

A. Sodium and potassium
B. Calcium and potassium
C. Calcium and magnesium
D. Sodium and magnesium

Answer 412

C. Calcium and magnesium

Question 413

The standard inoculum size for agar dilution susceptibility testing is:

A. 1 × 10^4 CFU/mL
B. 5 × 10^5 CFU/mL
C. 1 × 10^7 CFU/mL
D. 5 × 10^8 CFU/mL

Answer 413

A. 1 × 10^4 CFU/mL

Question 414

A chromogenic cephalosporin is used to detect resistance to:

A. Macrolides
B. Aminoglycosides
C. β-lactams
D. Tetracyclines

Answer 414

C. β-lactams

Question 415

All of the following media used for the cultivation of Micrococcaceae are SELECTIVE except:

A. 5% sheep blood agar
B. Phenyl-ethyl alcohol agar
C. Mannitol salt agar
D. Colistin nalidixic acid agar

Answer 415

A. 5% sheep blood agar

Question 416

Necrotizing fasciitis is a serious infection associated with:

A. Streptococcus agalactiae
B. Streptococcus mitis
C. Streptococcus pyogenes
D. Staphylococcus epidermidis

Answer 416

C. Streptococcus pyogenes

Question 417

Which organism produces the CAMP factor enhancing beta hemolysis in the presence of the S. aureus beta lysin?

A. Group A streptococci
B. Group B streptococci
C. Group C streptococci
D. Group D streptococci

Answer 417

B. Group B streptococci

Question 418

Optochin sensitivity is used to differentiate:

A. Streptococcus pneumoniae from other alpha-hemolytic streptococci
B. Streptococcus pyogenes from Streptococcus pneumoniae
C. Streptococcus agalactiae from Streptococcus pyogenes
D. Enterococci from non–group D enterococci

Answer 418

A. Streptococcus pneumoniae from other alpha-hemolytic streptococci

Question 419

Which organism is able to hydrolyze esculin and is a serious nosocomial pathogen?

A. S. bovis
B. S. mitis
C. E. faecalis
D. S. pneumoniae

Answer 419

C. E. faecalis

Enterococci are one of the most feared nosocomial pathogens isolated from the urinary tract, peritoneum, heart tissue, bacteremia, endocarditis, and intra-abdominal infections.

Question 420

Pulmonary anthrax is also known as:

A. Black eschar
B. Woolsorters’ disease
C. Legionnaires’ disease
D. Plague

Answer 420

B. Woolsorters’ disease

Question 421

A large, aerobic, gram-positive, spore-forming rod is isolated from ablood culture. It can be further confirmed as B. anthracis if it is:

A. Hemolytic and motile
B. Hemolytic and nonmotile
C. Nonhemolytic and motile
D. Nonhemolytic and nonmotile

Answer 421

D. Nonhemolytic and nonmotile

Question 422

EYE CULTURE, GRAM-POSITIVE, AEROBIC, MOTILE & BETA-HEMOLYTIC
A large, aerobic, beta-hemolytic, gram-positive rod is isolated from an eye culture. Subsequent testing reveals it is motile and produces a wide zone on egg yolk agar. The most likely identification of this organism is:

A. Bacillus anthracis
B. Escherichia coli
C. Bacillus cereus
D. Clostridium perfringens

Answer 422

C. Bacillus cereus

Question 423

It is a serious pathogen of the eye, causing progressive endophthalmitis:

A. Bacillus anthracis
B. Bacillus cereus
C. Bacillus subtilis
D. Bacillus thurigiensis

Answer 423

B. Bacillus cereus

Question 424

Pregnant women and immunocompromised patients should avoid eating which of the following foods to prevent Listeria infection

A. Feta cheese
B. Peanuts
C. Pickles
D. Ice cream

Answer 424

A. Feta cheese

Question 425

All of the following can be used to detect toxin from C. diphtheriae except:

A. Guinea pig lethality test
B. Elek test
C. Modified Tinsdale
D. PCR

Answer 425

C. Modified Tinsdale

Question 426

Which organism exhibits end-over-end tumbling motility when incubated in nutrient broth at room temperature for 1 to 2 hours

A. C. diphtheriae
B. C. jeikeium
C. Arthrobacter sp.
D. L. monocytogenes

Answer 426

D. L. monocytogenes

Question 427

Which of the following is the only catalase-negative, gram-positive, non-spore-forming rod that produces H2S on TSI?

A. Gardnerella sp.
B. Erysipelothrix sp.
C. Lactobacillus sp.
D. Arcanobacterium sp.

Answer 427

B. Erysipelothrix sp.

Question 428

Which organisms may stain partially acid-fast when stained with a modified acid-fast stain?

A. Gordonia sp.
B. Rhodococcus sp.
C. Nocardia sp.
D. All of the above

Answer 428

D. All of the above

If the modified acid-fast stain results are positive, the isolate is a probable partially acid-fast aerobic actinomycete (i.e., Nocardia, Rhodococcus, Tsukamurella, or Gordonia sp).

Question 429

Which organism is most commonly associated with human disease, particularly in immunocompromised patients, such as those infected with HIV?

A. Nocardia asteroides
B. Rhodococcus equi
C. Gordonia sp.
D. Tsukamurella sp.

Answer 429

B. Rhodococcus equi

To date, Rhodococcus equi has been the organism most commonly associated with human disease, particularly in immunocompromised patients, such as those infected with the human immunodeficiency virus (HIV).

Question 430

Infection caused by non–acid-fast aerobic actinomycetes is usually chronic, granulomatous lesions of the skin referred to as:

A. Mycelium
B. Necrosis
C. Impetigo
D. Mycetoma

Answer 430

D. Mycetoma

Question 431

Which actinomycete is partial acid-fast, has extensive aerial hyphae, and is lysozyme resistant?

A. Nocardia sp.
B. Rhodococcus sp.
C. Gordonia sp.
D. Tsukamurella sp.

Answer 431

A. Nocardia sp.

Question 432

Which Nocardia sp. causes more than 80% of human infections?

A. N. asteroides
B. N. brasiliensis
C. N. otitidiscaviarum
D. N. farcina

Answer 432

A. N. asteroides

Question 433

Incubation of which organism at 25°C produces a characteristic yellow pigment?

A. C. sakazakii
B. P. shigelloides
C. E. aerogenes
D. H. alvei

Answer 433

A. C. sakazakii

Question 434

Enterobacteriaceae are typically gram negative and:

A. Non–glucose fermenters
B. Capable of reducing nitrates to nitrites
C. Catalase negative
D. Oxidase positive

Answer 434

B. Capable of reducing nitrates to nitrites

Question 435

A patient presents with diarrhea and abdominal cramping. The organism isolated from the stool culture is identified as S. dysenteriae (group A). The TSI reaction would have indicated:

A. K/K
B. K/NC H2S+
C. A/A
D. K/A

Answer 435

D. K/A

Question 436

The most common cause of hemolytic uremic syndrome is:

A. EPEC
B. EAEC
C. O157:NM
D. O157:H7

Answer 436

D. O157:H7

Question 437

Which E. coli produces a heat-labile (LT) enterotoxin and a heat-stable enterotoxin?

A. UPEC
B. ETEC
C. MNEC
D. EHEC

Answer 437

B. ETEC

Question 438

A patient presents to the physician with pain and frequency of urination. The urine culture reveals a non–lactose fermenting, gram-negative rod with characteristic swarming on blood agar. The biochemical test that would specifically distinguish this organism from other Enterobacteriaceae is:

A. Lactose fermentation
B. Oxidase
C. Phenylalanine deaminase and H2S
D. Triple sugar iron agar

Answer 438

C. Phenylalanine deaminase and H2S

Question 439

Which organism has large, smooth, glistening colonies with a lavender pigment and smells like ammonia?

A. Acinetobacter spp.
B. Bordetella spp.
C. Stenotrophomonas sp.
D. Burkholderia sp.

Answer 439

C. Stenotrophomonas sp.

Question 440

Which organisms are plump coccobacilli that may resist decolorization and may be mistaken for Neisseria spp?

A. Acinetobacter spp.
B. Bordetella spp.
C. Stenotrophomonas sp.
D. Burkholderia sp.

Answer 440

A. Acinetobacter spp.

Question 441

Which of the following is the key pathogen that infects the lungs of patients with cystic fibrosis?

A. B. cepacia
B. B. pseudomallei
C. P. fluorescens
D. P. aeruginosa

Answer 441

D. P. aeruginosa

Question 442

Which of the following culture characteristics alert the microbiologist to a possible infection resulting from Eikenella corrodens?

A. Rapid growth on 5% sheep blood, chocolate, and MacConkey agar
B. Pitting of the agar and a characteristic chlorine bleach smell
C. Growth with alpha hemolysis on the 5% sheep blood agar and no growth on MAC agar
D. Limited growth on 5% sheep blood, chocolate, and MacConkey agar, but improved growth using BYCE media

Answer 442

B. Pitting of the agar and a characteristic chlorine bleach smell

Question 443

Into which genus have Haemophilus aphrophilus and Haemophilus paraphrophilus been recently reclassified?

A. Actinobacillus
B. Aggregatibacter
C. Haemophilus
D. Pasteurella

Answer 443

B. Aggregatibacter

Question 444

Which of the following conditions is viewed as a risk factor for systemic disease caused by Pasteurella multocida subsp. multocida?

A. Liver cirrhosis
B. End-stage renal disease
C. Hyperlipidemia
D. Hereditary hemochromatosis

Answer 444

A. Liver cirrhosis

Question 445

Which of the following Haemophilus species is an agent of a sexually transmitted disease?

A. H. parainfluenzae
B. H. influenzae
C. H. ducreyi
D. H. segnis

Answer 445

C. H. ducreyi

Question 446

All of the following organisms require X and V factors, except:

A. H. influenzae
B. H. haemolyticus
C. H. influenzae biotype aegyptius
D. Aggregatibacter aphrophilus

Answer 446

D. Aggregatibacter aphrophilus

Question 447

Which encapsulated type of H. influenzae is most common?

A. Type a
B. Type b
C. Type c
D. Type d

Answer 447

B. Type b

Question 448

Bartonella quintana has been known to cause:

A. Carrion’s disease
B. Trench fever
C. Cat-scratch disease
D. Lyme disease

Answer 448

B. Trench fever

Question 449

Which of the following has been recognized in postinfectious complications of a Campylobacter jejuni infection?

A. Guillain-Barré syndrome
B. Chronic pulmonary disease
C. Encephalitis
D. Endocarditis

Answer 449

A. Guillain-Barré syndrome

Question 450

A 60-year-old man suffered from fever, watery diarrhea, abdominal pain, and nausea. Three weeks later, he was admitted to the hospital unable to speak but coherent and oriented. Neurological examination revealed bilateral muscle weakness in his legs. Within hours, the muscle weakness extended to his arms and chest. He was diagnosed with Guillain–Barré syndrome. With which organism was he most likely infected?

A. Campylobacter jejuni
B. Clostridium tetani
C. Cytolmegalovirus
D. Salmonella enterica
E. Shigella sonnei

Answer 450

A. Campylobacter jejuni

Question 451

All of the following agars may be used to isolate Helicobacter except:

A. Campy-CVA
B. Skirrow’s
C. Thiosulfate-citrate-bile salts-sucrose agar (TCBS)
D. modified Thayer-Martin

Answer 451

C. Thiosulfate-citrate-bile salts-sucrose agar (TCBS)

Stool specimens submitted for culture of H. cinaedi and H. fennelliae are inoculated onto selective media used for Campylobacter isolation but without cephalothin such as Campy-CVA.
For the recovery of H. pylori from tissue biopsy specimens including gastric antral biopsies, non-selective agar media, including chocolate agar and Brucella agar with 5% sheep blood, have resulted in successful recovery of the organisms.
Selective agar such as Skirrow’s and modified Thayer-Martin agar also support growth.

Question 452

Proper media for culture of a urethral discharge from a man include:

Sheep blood and phenylethyl alcohol agars
Eosin-methylene blue and sheep blood agars
Thioglycollate broth and chocolate agar
Chocolate and modified Thayer-Martin agars

Answer 452

Chocolate and modified Thayer-Martin agars

Chocolate agar and chocolate agar based selective media should be used for recovery of
Neisseria gonorrhoeae from urethral discharge.
Chocolate agar provides the nutrients required by N. gonorrhoeae and selective media
contains antimicrobial agents that inhibits other organisms and permits recovery of
pathogenic Neisseria.

Question 453

The proper blood-to-broth ratio for blood cultures to reduce the antibacterial effect of serum in adults is:

1:2
1:3
1:10
1:30

Answer 453

1:10

Human blood contains substance that may inhibit microbial growth.
Diluting blood in culture broth reduces the concentration of these substances as well as
any antibiotics that may be present.
The recommended blood-broth ratio is 1:5 to 1:10.
Dilutions less than this may cause blood to clot, trapping microorganisms in the clot.
Greater dilutions may increase the time of detection.

Question 454

In the Kirby-Bauer disc diffusion susceptibility test, which variable is critical when testing Pseudomonas species for antibiotic susceptibility to aminoglycosides?

Incubation temperature
Duration of incubation
Cation content of the media
Depth of the aga

Answer 454

Cation content of the media

Variations in the concentrations of divalent cations, primarily calcium and magnesium affect the results of aminoglycoside, tetracycline and colistin test with Pseudomonas
aeruginosa isolates.
A cation concentration that is too high results in smaller zone sized and a concentration
that is too low increase zone sizes.

Question 455

Susceptibility testing performed on quality control organisms using a new media lot number yielded zone sizes that were too large for all antibiotics
tested. The testing was repeated using media from a previously used lot number, and all zone sizes were acceptable. Which of the following best
explains the unacceptable zone sizes?

The antibiotic disks were not stored with the proper desicant
The depth of the media was too thick
The depth of the media was too thin
The antibiotic disks were not properly applied to the media

Answer 455

The depth of the media was too thin

All Mueller Hinton Agar used for disk diffusion susceptibility testing should be poured to a
depth of 4mm.
If the depth of the media is <4mm, this may be associated with excessively large zones
and false positive susceptibility results.
Agar that is >4mm in depth may cause excessively small zone sizes.

Question 456

Which type of microscope would be most useful in examining viruses and the structure of microbial cells?

Electron
Phase-contrast
Dark-field
Bright-field

Answer 456

Electron

Due to the small size of viruses, they are not visible using light microscopy.
Electron microscopy is used to visualize viruses and the internal structure of microorganisms.

Question 457

After satisfactory performance of daily disk diffusion susceptibility quality control is documented, the frequency of quality control can be reduced to:

Twice a week
Every week
Every other week
Every month

Answer 457

Every week

Daily disk diffusion quality control can be converted to weekly testing when 30 days of
consecutive testing demonstrated no more than 3 antibiotic/ organism combinations
outside the acceptable limits.

Question 458

The most common cause for failure of a GasPakä anaerobic jar to establish an adequate environment for anaerobic incubation is:

-The failure of the oxidation-reduction potential indicator system due to deterioration of methylene blue
-The failure of the packet to generate adequate H2 and/or CO2
-Condensation of water on the inner surface of the jar
-Catalysts that have become inactivated after repeated use

Answer 458

Catalysts that have become inactivated after repeated use

The two (2) most common causes of failure of GasPak system is a defective gasket in the
jar lid that allows escape of gas from inside the jar and inactivated catalyst pellets.

Question 459

Which of the following is the most appropriate method for collecting a urine specimen from a patient with an indwelling catheter?

-Remove the catheter, cut the tip, and submit it for culture
-Disconnect the catheter from the bag, and collect urine from the terminal end of the
catheter
-Collect urine directly from the bag
-Aspirate urine aseptically from the catheter tubing

Answer 459

Aspirate urine aseptically from the catheter tubing

Indwelling catheters are closed systems, and should not be disconnected for specimen
collection.
Urine samples should not be collected from catheter bags, and Foley catheter tips are
unsuitable for culture because they are contaminated with colonizing organisms.
Urine from indwelling catheters should be collected by aseptically puncturing the tubing
(collection port).

Question 460

Which one of the following specimen requests is acceptable?

Feces submitted for anaerobic culture
Foley catheter tip submitted for aerobic culture
Rectal swab submitted for direct smear for gonococci
Urine for culture of acid-fast bacilli

Answer 460

Urine for culture of acid-fast bacilli

Urine is an appropriate specimen for the detection of renal tuberculosis.

Since feces contain anaerobic organisms as part of the indigenous flora, it is an
unacceptable specimen for anaerobic culture.

Foley catheter tips are also not acceptable for culture because they are contaminated with colonizing organisms.

Gram stain smears of rectal swabs for N. gonorrhoeae should also not be performed, since the presence of organisms with similar morphologies may lead to over interpretation
of smears.

Question 461

SPS is used as an anticoagulant for blood cultures because it:

Inactivates penicillin and cephalosporins
Prevents clumping of red cells
Inactivates neutrophils and components of serum complement
Facilitates growth of anaerobes

Answer 461

Inactivates neutrophils and components of serum complement

Most commercially available blood culture media contain sodium polyanethol sulfonate (SPS) in concentration between 0.025 and 0.050%.

SPS has anticoagulant activity and inactivates neutrophils as well as some antibiotics including gentamicin and polymyxin.

It also precipitates components of serum complement

Question 462

In a disk diffusion susceptibility test, which of the following can result if disks are placed on the inoculated media and left at room temperature
for an hour before incubation?

The antibiotic would not diffuse into the medium, resulting in no zone
Zones of smaller diameter would result
Zones of larger diameter would result
There would be no effect on the final zone diameter

Answer 462

Zones of larger diameter would result

A delay of more than 15 minutes between placing the disks on an inoculated plate and
incubation permits excess prediffusion of the antimicrobial agent from the disk. This
would result in a larger than expected zone diameter.

Question 463

Which of the following factors would make an organism appear to be
more resistant on a disk diffusion susceptibility test?

Too little agar on the plate
Too many organisms in the inoculum
The presence of 0.5% NaCl in the medium
A medium with pH of 7.4

Answer 463

Too many organisms in the inoculum

To ensure the reproducibility of disk diffusion testing, the inoculum must be standardized.
If the inoculum is too dense (too many organisms) zone sizes would be smaller than
expected and appear falsely resistant.

Question 464

The optimal wound specimen for culture of anaerobic organisms should be:

A swab of lesion obtained before administration of antibiotics
A swab of lesion obtained after administration of antibiotics
A syringe filled with pus, obtained before administration of antibiotics
A syringe filled with pus, obtained after administration of antibiotics

Answer 464

A syringe filled with pus, obtained before administration of antibiotics

The use of swabs for collection of specimens for anaerobic culture is discouraged.
Aspiration with a needle and syringe is recommended. Whenever possible cultures should
be obtained before the administration of antibiotics to optimize organism recovery

Question 465

A 21-year-old patient presents with pharyngitis. A throat swab is collected and submitted for anaerobic culture. This specimen should be:

Set-up immediately
Rejected as unacceptable
Inoculated into thioglycollate broth
Sent to reference laboratory

Answer 465

Rejected as unacceptable

Many anaerobic bacteria are commensal flora in the oropharynx. Anaerobic bacteria do
not cause pharyngitis. The most common cause of pharyngitis is Streptococcus pyogenes. Other causes include Arcanobacterium haemolyticum, Corynebacterium
diphtheriae, Neisseria gonorrhoeae and viruses.

Question 466

Which of the following tests is used to monitor bactericidal activity during antimicrobic therapy in cases of endocarditis?

Elek
Tolerance
Sherris synergism
Schlichter

Answer 466

Schlichter

The serum bactericidal, or Schlichter test can be used to assess the activity of patient’s
serum when they are receiving long term therapy for endocarditis or osteomyelitis. High
titers of antibacterial activity in the serum suggest adequate dosing, a non-tolerant isolate
or normal elimination of the antibiotic.

Question 467

Quality control results for disk diffusion susceptibility tests yield the
following results: aminoglycoside zones too small and penicillin zones too large. This is most likely due to the:

Inoculum being too heavy
Inoculum being too light
pH of Mueller-Hinton agar being too low
Calcium and magnesium concentration in the agar being too high

Answer 467

pH of Mueller-Hinton agar being too low

Mueller-Hinton Agar used for disk diffusion is standardized at pH 7.2 to 7.4.
Penicillins function better in an acidic environment, so zone sizes would become larger id
the media pH is too low.
Aminoglycosides, on the other hand are less effective in an acidic environment, so zone
sizes would become smaller if the pH of the media is too low.
Plates should not be incubated in carbon dioxide atmosphere which lowers the pH of the
media.

Question 468

Which of the following is the most important variable in the recovery of organisms in patients with bacteremia?

Subculture of all bottles at day 5 of incubation
The volume of blood cultured
Use of chlorhexidine for skin antisepsis
Collection of multiple blood culture sets from a single venipuncture

Answer 468

The volume of blood cultured

The volume of blood collected is the single most important variable in the recovery of
organisms in patients with bloodstream infections.
Since many cases of adult bacteremia are of low magnitude, there is a direct relationship
between the yield of blood culture (positivity) and the volume of blood collected.

Question 469

To quality control the autoclave, a vial of Bacillus stearothermophilus is autoclaved and should than be:

Inoculated to blood agar
Incubated at 37C
Inoculated to chocolate agar
Incubated at 56C

Answer 469

Incubated at 56C

Bacillus stearothermophilus is commonly used as an indicator organism for the
appropriate functioning of autoclaves.
Unlike most Bacillus species, B. stearothermophilus grows at 56˚C.

Question 470

In a quality control procedure on a new batch of Mueller-Hinton plates using a stock culture of Staphylococcus aureus (ATCC 25923), all the
disk zone sizes are too small. The most likely reason for this is that the:

Mueller-Hinton plates were poured too thin
Potency of the antibiotic disks is too high
Bacterial suspension was not diluted to the proper concentration
Disks should have been set up on mannitol salt

Answer 470

Bacterial suspension was not diluted to the proper concentration

Quality control zone sizes that are too small could indicate that the organism inoculum is too high, plate were poured too thick or that the potency of the antibiotic disks is too low.

Question 471

A urine Gram stain shows gram-positive cocci in clusters. The organism tested catalase positive. To speciate this organism from culture, the technician should perform a coagulase test and a/an:

Polymyxin B susceptibility
Novobiocin susceptibility
Oxidase
Beta-lactamase

Answer 471

Novobiocin susceptibility

The organism in this urine culture is a Staphylococcus species.
Coagulase will differentiate S. aureus from coagulase negative staphylococci (CNS) and
novobiocin susceptibility will differentiate S. saprophyticus from other CNS.

Question 472

The enterotoxin produced by certain strains of hemolytic, coagulase positive Staphylococcus aureus:

Is destroyed by boiling for 15-30 minutes
Identical to the dermonecrotic toxin
Causes one type of bacterial food poisoning
Highly antigenic

Answer 472

Causes one type of bacterial food poisoning

Staphylococcus aureus produces an enterotoxin that is associated with short incubation
food poisoning.

Question 473

Gram stain examination from a blood culture bottle shows dark blue,
spherical organisms in clusters. Growth on sheep blood agar shows small, round, pale yellow colonies. Further tests should include:

Catalase production and coagulase test
Bacitracin susceptibility and serological typing
Oxidase and deoxyribonuclease reactions
Voges-Proskauer and methyl red reactions

Answer 473

Catalase production and coagulase test

The gram stain and culture growth describe a Staphylococcus species. Catalase
production confirms that the organism belong to the genus Staphylococcus and
coagulase is used to differentiate S. aureus from coagulase negative staphylococci.

Question 474

A beta-hemolytic, catalase-positive, gram-positive coccus is coagulase negative by the slide coagulase test. Which of the following is the most
appropriate action in identification of this organism?

Report a coagulase-negative Staphylococcus
Report a coagulase-negative Staphylococcus aureus
Reconfirm the hemolytic reaction on a fresh 24-hour culture
Do a tube coagulase test to confirm the slide test

Answer 474

Do a tube coagulase test to confirm the slide test

Staphylococcus aureus are usually beta hemolytic. Some strains may not produce bound
coagulase detected by the slide coagulase test. A tube coagulase is performed to detect
free coagulase and should be performed on colonies with typical S. aureus morphology
that are slide coagulase-negative.

Question 475

During the past month, Staphylococcus epidermidis has been isolated
from blood cultures at 2-3 times the rate from the previous year. The
most logical explanation for the increase in these isolates is that:

The blood culture media are contaminated with this organism
The hospital ventilation system is contaminated with Staphylococcus epidermidis
There has been a break in proper skin preparation before drawing blood for culture
A relatively virulent isolate is being spread from patient to patient

Answer 475

There has been a break in proper skin preparation before drawing blood for culture

Appropriate skin antisepsis is the most important factor in preventing contaminated blood cultures. Staphylococcus epidermidis is a common blood culture contaminant because it is a common inhabitant of the skin.

Question 476

An outbreak of Staphylococcus aureus has occurred in a hospital nursery. In order to establish the epidemiological source of the outbreak, the most commonly used typing method is:

Pulsed-field gel electrophoresis
Serological typing
Coagulase testing
Catalase testing

Answer 476

Pulsed-field gel electrophoresis

The most commonly used method to determine the relatedness of 2 or more bacterial
strains is pulsed-field gel electrophoresis.

Question 477

Specimens should be collected during the _______ of an illness and before
antibiotics are administered, if possible.

Acute phase
Chronic phase

Answer 477

Acute phase

Specimens should be collected during the acute (early) phase of an illness (or within 2 to 3
days for viral infections) and before antibiotics are administered, if possible.

Question 478

For wound specimen, wipe area with:

10% potassium hydroxide
70% alcohol
Formalin
Hydrogen peroxide

Answer 478

70% alcohol

Question 479

CSF collected from a shunt:

BAP, MAC
BAP, CAP
CAP, MAC
BAP, CAP, THIO

Answer 479

BAP, CAP, THIO

CSF
BA, CA (Routine)
BA, CA, thio (Shunt)

Question 480

Serum for serologic studies may be stored for up to 1 week:

4C
25C
37C
-20C

Answer 480

-20C

Urine, stool, viral specimens, sputa, swabs, and foreign devices such as catheters should
be stored at 4° C. Serum for serologic studies may be frozen for up to 1 week at –20°C,
and tissues or specimens for long-term storage should be frozen at –70°C.

Question 481

Blood agar is considered:

Nutritive medium
Selective medium
Differential medim
Nutritive and selective medium
Nutritive and differential medium

Answer 481

Nutritive and differential medium

Blood agar is considered both a nutritive and differential medium because it differentiates
organisms based on whether they are alpha (α)-, beta (β)-, or gamma (γ)- hemolytic.

Question 482

Moderate growth; growth is out to the third quadrant:

1+
2+
3+
4+

Answer 482

3+

Numbers of organisms present can subse- quently be graded as 4+ (many, heavy growth)
if growth is out to the fourth quadrant, 3+ (moderate growth) if growth is out to the third
quadrant, 2+ (few or light growth) if growth is in the second quadrant, and 1+ (rare) if
growth is in the first quadrant.

Question 483

Anaerobes usually cannot grow in the presence of O2, and the atmosphere in anaerobe jars, bags, or chambers is composed of:

5 to 10% O2, 5 to 10% CO2, 80 to 90% N2
5 to 10% N2, 5 to 10% CO2, 80 to 90% H2
5 to 10% CO2, 80 to 90% H2, 0% O2
5 to 10% H2, 5 to 10% CO2, 80 to 90% N2, 0% O2

Answer 483

5 to 10% H2, 5 to 10% CO2, 80 to 90% N2, 0% O2

Anaerobes usually cannot grow in the presence of O2, and the atmosphere in anaerobe
jars, bags, or chambers is composed of 5% to 10% hydrogen (H2), 5% to 10% CO2, 80% to
90% nitrogen (N2), and 0% O2.

Question 484

Grows at the bottom of the thioglycollate broth:

Strict aerobes
Strict anaerobes
Microaerophilic organisms
Facultative anaerobes

Answer 484

Strict anaerobes

In addition to amount of growth present, the location of growth within thioglycollate broth
indicates the type of organism present based on oxygen requirements.

Strict anaerobes will grow at the bottom of the broth tube, whereas aerobes will grow near
the surface.

Microaerophilic organisms will grow slightly below the surface where oxygen
concentrations are lower than atmospheric concentrations.

In addition, facultative anaerobes and aerotolerant organisms will grow throughout the
medium, as they are unaffected by the variation in oxygen content.

Question 485

Grows near the surface of the thioglycollate broth:

Strict aerobes
Strict anaerobes
Microaerophilic organisms
Facultative anaerobes

Answer 485

Strict aerobes

In addition to amount of growth present, the location of growth within thioglycollate broth
indicates the type of organism present based on oxygen requirements.

Strict anaerobes will grow at the bottom of the broth tube, whereas aerobes will grow near the surface.

Microaerophilic organisms will grow slightly below the surface where oxygen concentrations are lower than atmospheric concentrations.

In addition, facultative anaerobes and aerotolerant organisms will grow throughout the medium, as they are unaffected by the variation in oxygen content.

Question 486

In thioglycollate broth, these organisms will grow slightly below the
surface where oxygen concentrations are lower than atmospheric concentrations:

Strict aerobes
Strict anaerobes
Microaerophilic organisms
Facultative anaerobes

Answer 486

Microaerophilic organisms

In addition to amount of growth present, the location of growth within thioglycollate broth
indicates the type of organism present based on oxygen requirements.

Strict anaerobes will grow at the bottom of the broth tube, whereas aerobes will grow near the surface.

Microaerophilic organisms will grow slightly below the surface where oxygen
concentrations are lower than atmospheric concentrations.

In addition, facultative anaerobes and aerotolerant organisms will grow throughout the medium, as they are unaffected by the variation in oxygen content.

Question 487

In thioglycollate broth, these organisms will grow throughout the medium:

Strict aerobes
Strict anaerobes
Microaerophilic organisms
Facultative anaerobes

Answer 487

Facultative anaerobes

In addition to amount of growth present, the location of growth within thioglycollate broth
indicates the type of organism present based on oxygen requirements.

Strict anaerobes will grow at the bottom of the broth tube, whereas aerobes will grow near the surface.

Microaerophilic organisms will grow slightly below the surface where oxygen
concentrations are lower than atmospheric concentrations.

In addition, facultative anaerobes and aerotolerant organisms will grow throughout the
medium, as they are unaffected by the variation in oxygen content.

Question 488

Media employ some factor (or factors) that allows colonies of one bacterial species or type to exhibit certain metabolic or culture
characteristics that can be used to distinguish it from other bacteria growing on the same agar plate:

Nutritive media
Enrichment media
Selective media
Differential media

Answer 488

Differential media

Question 489

Interferes with folic acid pathway by binding the enzyme dihydropteroate synthase:

Aminoglycosides
Chloramphenicol
Penicillin
Sulfonamides

Answer 489

Sulfonamides

Question 490

Monobactams:

Inhibits cell wall synthesis
Inhibits protein synthesis
Inhibits nucleic acid synthesis
Alters cell membrane

Answer 490

Inhibits cell wall synthesis

Question 491

Bone marrow toxicity is the major side effect associated with:

Cephalosporin
Chloramphenicol
Penicillin
Sulfonamide

Answer 491

Chloramphenicol

Question 492

The 0.5 McFarland standard, which is commercially available, provides an
optical density comparable to the density of a bacterial suspension of:

0.5 x 10 8th CFU/mL
1.0 x 10 8th CFU/mL
1.5 x 10 8th CFU/mL
2.0 x 10 8th CFU/mL

Answer 492

1.5 x 10 8th CFU/mL

Question 493

Composition of McFarland standard:

1% hydrochloric acid and 1.175% barium chloride
2% hydrochloric acid and 1.175% barium chloride
1% sulfuric acid and 1.175% barium chloride
2% sulfuric acid and 2.175% barium chloride

Answer 493

1% sulfuric acid and 1.175% barium chloride

McFarland turbidity standards, prepared by mixing 1% sulfuric acid and 1.175% barium
chloride to obtain a solution with a specific optical density, are commonly used.

The 0.5 McFarland standard, which is commercially available, provides an optical density
comparable to the density of a bacterial suspension of 1.5 × 108 colony forming units
(CFU) per milliliter.

Question 494

Diffusion of the drug in the agar establishes a concentration gradient from high ________ to low _______.

High (periphery of plate) to low (center of plate)
High (center of plate) to low (periphery of plate)

Answer 494

High (center of plate) to low (periphery of plate)

Question 495

In disk diffusion susceptibility testing, as an antimicrobial agent diffuses
away from the disk, the concentration of antibiotic is:

Increased
Decreased
Unchanged
Inoculum dependent

Answer 495

Decreased

The amount of antibiotic used in disk diffusion susceptibility testing is standardized and constant.

Once the disk is placed on the inoculated plate and makes contact with the agar, the antibiotic in the disk begins to diffuse out.

As it diffuses into the media, the concentration of antibiotic gets lower the further it
diffuses from the disk.

Question 496

Differentiate clindamycin resistance among S. aureus:

Aminoglycoside screens
D zone test
Oxacillin agar screen
Vancomycin agar screen

Answer 496

D zone test

Question 497

A yellow colony from a wound culture tested catalase-positive and coagulase-negative. The organism stained as gram-positive cocci in
clusters. Which of the following tests would differentiate between a
coagulase-negative Staphylococcus and Micrococcus?

Novobiocin susceptibility
Leucine aminopeptidase production
Furazolidone (100 ug/disk) susceptibility
Bile esculin

Answer 497

Furazolidone (100 ug/disk) susceptibility

Micrococcus and Staphylococcus can be differentiated by susceptibility to furazolidone
(100 μg/disk). Staphylococcus is susceptible and Micrococcus is resistant.

Question 498

A light yellow colony from a skin lesion grew aerobically and tested as catalase positive and coagulase negative. The organism gram stained as positive cocci in clusters. The organism was modified oxidase positive,
bacitracin (0.04U) susceptible and resistant to lysostaphin. What is the identification of this organism?

Staphylococcus aureus
Micrococcus luteus
Staphylococcus epidermidis
Peptostreptococcus anaerobius

Answer 498

Micrococcus luteus

Micrococcus is modified oxidase positive, bacitracin (0.04U) susceptible and resistant to
lysostaphin.

Question 499

Staphylococcus aureus toxin which disrupts the smooth muscle in blood
vessels and is toxic to erythrocytes, leukocytes, hepatocytes, and
platelets:

Alpha toxin
Beta toxin
Delta toxin
Gamma toxin

Answer 499

Alpha toxin

Most strains of S. aureus produce ALPHA toxin, which disrupts smooth muscle in blood
vessels and is toxic to erythrocytes, leukocytes, hepatocytes, and platelets.

The BETA toxin, believed to work in conjunction with the alpha toxin, is a heat-labile
sphingomyelinase, which catalyzes the hydrolysis of membrane phospholipids resulting in
cell lysis.

S. aureus, S. epidermidis, and S. haemolyticus have been identified as capable of
producing DELTA toxin, which is cytolytic to erythrocytes and demonstrates nonspecific
membrane toxicity to other mammalian cells.

GAMMA toxin is produced by all strains of S. aureus and may actually function in
association with the Panton-Valentine leukocidin (PVL).

Question 500

The minimum concentration of antimicrobial agent needed to prevent
visually discernible growth of a bacterial or fungal suspension.

Minimum bactericidal concentration (MBC)
Minimum inhibitory concentration (MIC)
Both of these
None of these

Answer 500

Minimum inhibitory concentration (MIC)

Minimum inhibitory concentration (MIC)
The minimum concentration of antimicrobial agent needed to prevent visually discernible
growth of a bacterial or fungal suspension.

Minimum bactericidal concentration (MBC)
The minimum concentration of antimicrobial agent needed to yield a 99.9% reduction in
viable colony-forming units of a bacterial or fungal suspension.

Question 501

To read the hemolytic reaction on a blood agar plate accurately, the technologist must hold the plate up to the light and observe the plate
with:

Direct light
Natural light
Reflected light
Transmitted light

Answer 501

Transmitted light

To read the hemolytic reaction on a blood agar plate accurately, the technologist must
hold the plate up to the light and observe the plate with the light coming from behind (i.e.,
transmitted light).

Question 502

A sheep blood agar plate is used as a primary isolation medium when all
of the following organisms are to be recovered from a wound specimen except:

β-Hemolytic streptococci and coagulase-positive staphylococci
Haemophilus influenzae and Haemophilus parainfluenzae
Proteus spp. and Escherichia coli
Pseudomonas spp. and Acinetobacter spp.

Answer 502

Haemophilus influenzae and Haemophilus parainfluenzae

Both gram-positive cocci and gram-negative bacilli will grow on blood agar plates, but the
medium is used in conjunction with a selective medium such as CNA agar for grampositive cocci and MacConkey agar for gram-negative bacilli. H. influenzae requires X and
V factors, and H. parainfluenzae requires V factor; the primary isolation medium for
Haemophilus is chocolate agar.

Question 503

An emergency department physician ordered a culture and sensitivity test on a catheterized urine specimen obtained from a 24-year-old female patient. A colony count was done and gave the following results after 24 hours:

Blood agar plate = >100,000 col/mL of gram-positive cocci resembling
staphylococci
MacConkey agar = No growth
CNA plate = Inhibited growth
Catalase = Positive
Hemolysis = Neg
Novobiocin = Resistant

Staphylococcus saprophyticus
Micrococcus luteus
Staphylococcus aureus
Streptococcus pyogenes

Answer 503

Staphylococcus saprophyticus

CNA inhibits most strains of S. saprophyticus. Therefore, blood agar should be used when
culturing catheterized urine samples from young female patients. Most S. saprophyticus
isolates are obtained from female patients 20–30 years old.

Question 504

An outbreak of Staphylococcus aureus in the nursery department prompted the Infection Control Committee to proceed with an environmental screening procedure. The best screening media to use for
this purpose would be:

CNA agar
THIO broth
Mannitol salt agar
PEA agar

Answer 504

Mannitol salt agar

The high concentration of NaCl (7.5%) in mannitol salt agar allows for the recovery of S. aureus from heavily contaminated specimens while inhibiting other organisms. Also, S. aureus ferments mannitol, thus allowing for easy detection of yellow-haloed colonies of S. aureus on red mannitol salt agar.

Question 505

A listless 12-month-old boy with a fever of 103°F was taken to the emergency department. He had been diagnosed with an ear infection 3
days earlier. A spinal tap was performed, but only one tube of CSF was obtained from the lumbar puncture. The single tube of CSF should be
submitted first to which department?

Chemistry
Microbiology
Hematology
Cytology/Histology

Answer 505

Microbiology

Generally, tube 2 is submitted to the microbiology laboratory for culture and Gram stain
smear. To ensure recovery of any pathogens and correct diagnosis without other bacterial
contamination, immediate centrifugation and inoculation to the appropriate media as well
as a Gram stain smear should be performed prior to delivery of the specimen to the
chemistry department for testing.

Question 506

A 65-year-old female outpatient was requested by her physician to submit a 24-hour urine specimen for protein and creatinine tests. He also
requested testing for mycobacteria in the urine. Should the microbiology
laboratory accept this 24-hour specimen for culture?

Yes, if the specimen is kept on ice
Yes, if the specimen is for aerobic culture only
No, the specimen must be kept at room temperature
No, the specimen is unsuitable for the recovery of mycobacteria

Answer 506

No, the specimen is unsuitable for the recovery of mycobacteria

In general, a 24-hour urine is unsuitable for culture; a first morning specimen is best for the
recovery of mycobacteria in the urine.

Question 507

A lymph node biopsy obtained from a 30-year-old male patient was
submitted to the microbiology laboratory for a culture and AFB smear for
mycobacteria. The specimen was fixed in formalin. This specimen should be:

Accepted for AFB smear and cultured
Rejected
Held at room temperature for 24 hours and then cultured
Cultured for anaerobes only

Answer 507

Rejected

Specimens submitted for culture and recovery of any bacteria should be submitted without fixatives.

Question 508

When testing for coagulase properties, staphylococci isolates from a 67-
year-old male diabetic patient showed a positive tube test (free coagulase). The organism should be identified as:

Staphylococcus aureus
Staphylococcus haemolyticus
Staphylococcus saprophyticus
Micrococcus luteus

Answer 508

Staphylococcus aureus

S. aureus is an opportunistic human pathogen. A wound or ulcer infected with S. aureus
that is left untreated is especially detrimental to a diabetic patient.

Question 509

An isolate of Staphylococcus aureus was cultured from an ulcer obtained
from the leg of a diabetic 79-year-old female patient. The organism
showed resistance to methicillin. Additionally, this isolate should be
tested for resistance or susceptibility to:

Erythromycin
Gentamicin
Vancomycin
Kanamycin

Answer 509

Vancomycin

MRSA isolates are usually tested for susceptibility or resistance to vancomycin, a glycopeptide.

Question 510

A catalase-positive, gram-positive coccus (clusters on Gram stain smear)
grew pale yellow, creamy colonies on 5% sheep blood agar. The specimen
was recovered from pustules on the face of a 5-year-old girl with impetigo.

Glucose = + (Fermentation)
PYR = Neg
Lysostaphin = Sensitive
Oxidase = Neg
Bacitracin = Sensitive

Micrococcus
Streptococcus
Enterococcus
Staphylococcus

Answer 510

Staphylococcus

S. aureus is a usual cause of skin infections and a common cause of cellulitis, impetigo,
postsurgical wounds, and scalded skin syndrome in infants.

Question 511

A wound (skin lesion) specimen obtained from a newborn grew predominantly β-hemolytic colonies of gram-positive cocci on 5% sheep
blood agar. The newborn infant was covered with small skin eruptions
that gave the appearance of a “scalding of the skin.” The gram-positive
cocci proved to be catalase positive. Which tests should follow for the
appropriate identification?

Optochin, bile solubility, PYR
Coagulase, glucose fermentation, DNase
Bacitracin, PYR, 6.5% salt broth
CAMP, bile-esculin, 6.5% salt broth

Answer 511

Coagulase, glucose fermentation, DNase

S. aureus is the cause of “scalded skin” syndrome in newborn infants. The production of a potent exotoxin (exfoliatin) causes the epidermis to slough off, leaving the newborn’s skin with a red, raw texture or a burned, scalded look.

Question 512

Fermentation end-products are often used to aid inthe identification of bacteria. Fermentation results in which of the following?

A. Conversion of glucose to pyruvate
B. Lactic acid, mixed acids, alcohols, CO2 production
C. CO2 and water
D. Specific teichoic acids

Answer 512

B. Lactic acid, mixed acids, alcohols, CO2 production

Question 513

The exchange of cellular DNA between two living bacterial cells that involves an intercellular bridge is which of the following processes?

A. Transformation
B. Transduction
C. Plasmidization
D. Conjugation

Answer 513

D. Conjugation

Question 514

Which of the following bacteria should be considered important pathogens when reading gram-stained smears of soft tissue abscess?

A. Streptococcus pneumoniae
B. Neisseria gonorrhoeae
C. Pseudomonas aeruginosa
D. Staphylococcus aureus

Answer 514

D. Staphylococcus aureus

Question 515

Which medium can be described as containing bile salts and dyes (bromothymol blue and acid fuchsin) to selectively slow the growth of most nonpathogenic gram-negative bacilli found in the gastrointestinal tract and allow Salmonella spp. and Shigella spp. to grow?

A. Thayer-Martin
B. MacConkey
C. PEA (phenylethyl alcohol)
D. Hektoen

Answer 515

D. Hektoen

Question 516

The slide coagulase test is a rapid screening test for the production of which of the following?

A. Clumping factor
B. Free coagulase
C. Extracellular coagulase
D. Catalase

Answer 516

A. Clumping factor

Question 517

The first identification test performed on a clinical isolate of gram-positive, catalase-positive cocci should be which of the following?

A. Penicillin test
B. Gram stain
C. Oxidase test
D. Coagulase test

Answer 517

D. Coagulase test

Question 518

The toxic shock syndrome toxin-1 is an important virulence factor in staphylococcal disease. This toxin is classified into which of the following groups of toxins?

A. Cytolytic toxin
B. Leukocidin
C. Phospholipase
D. Enterotoxin

Answer 518

D. Enterotoxin

Question 519

Within 5 hours of returning home from lunch at your most favorite fast food restaurant you feel very sick and are vomiting. Which of the following is the most likely causative organism?

A. Staphylococcus aureus
B. Vibrio parahaemolyticus
C. Shigella sonnei
D. Escherichia coli

Answer 519

A. Staphylococcus aureus

Question 520

The ability to grow well at refrigerator temperatures is a characteristic of which of the following organisms?

A. Mycobacterium gordonae
B. Listeria monocytogenes
C. Erysipelothrix
D. Bacillus cereus

Answer 520

B. Listeria monocytogenes

Question 521

A catalase-positive, gram-positive bacillus that is not acid-fast, does not branch, and does not form spores could possibly belong to which group of bacteria?

A. Corynebacterium
B. Bacillus
C. Nocardia
D. Mycobacterium

Answer 521

A. Corynebacterium

(Corynebacterium - no spores but has metachromatic granules;)
nocardia - partially acid fast
MTB - acid fast

Question 522

Which of the following sets of tests provide the best differentiation of Erysipelothrix from Listeria monocytogenes?

A. Gram-stained smear, oxidase, and optochin
B. Gram-stained smear, catalase, and motility
C. CAMP test, hydrogen sulfide production, esculin hydrolysis
D. Reverse CAMP, gram-stained smear, beta-hemolysis

Answer 522

C. CAMP test, hydrogen sulfide production, esculin hydrolysis

Question 523

Neonatal meningitis is an uncommon but significant disease. Two important causes of this disease may be somewhat difficult to differentiate on preliminary observation. Which of the following sets of tests provide the best differentiation of Streptococcus agalactiae from Listeria monocytogenes

A. Gram-stained smear, oxidase, and optochin
B. Gram-stained smear, catalase, and motility
C. CAMP test, hydrogen sulfide production, beta-hemolysis
D. Reverse CAMP, gram-stained smear, beta-hemolysis

Answer 523

B. Gram-stained smear, catalase, and motility

Question 524

Which of the following tests is important as a part of the genus identification or as part of a preliminary identification but is not used as a confirmatory identification of Bacillus anthracis?

A. Demonstration of a capsule
B. Demonstration of spore formation
C. Positive PCR test
D. Lysis of the strain by specific bacteriophages

Answer 524

B. Demonstration of spore formation

Question 525

A patient recently arrived in the United States from Africa presents with a long-standing cutaneous lesion, which is cultured for bacteria, fungi, and AFB. An AFB smear is made and is reported as positive for AFB. After 8 weeks of culture on both non-selective and selective AFB media, no colonies appear. Which of the following organisms should be suspected?

A. M. kansasii
B. M. tuberculosis
C. M. leprae
D. M. avium-intracellulare complex

Answer 525

C. M. leprae

Question 526

The swarming gram-negative bacillus that can be described as oxidase-negative, nitrate-positive, indole-negative, and H2S-positive is mostly likely which of the following?

A. Proteus aerogenes
B. Proteus vulgaris
C. Proteus mirabilis
D. Escherichia coli

Answer 526

C. Proteus mirabilis

Question 527

Organisms belonging to the genus Neisseria are described as which of the following?

A. Gram-positive diplococci
B. Gram-negative diplococci
C. Gram-negative coccobacilli
D. Gram-negative bacilli

Answer 527

B. Gram-negative diplococci

Question 528

Which of the following is the most sensitive method for the diagnosis of Chlamydia trachomatis?

A. Cytology
B. Culture
C. Nucleic acid amplification
d. Serologic testing

Answer 528

C. Nucleic acid amplification

Question 529

Pseudomembranous colitis caused by Clostridium difficile is best confirmed by which of the following laboratory findings?

A. Presence of the toxin in stool
B. Isolation of C. difficile from stool
C. Gas production in thioglycolate media
D. Gram stain of stool showing many gram-positive bacilli

Answer 529

A. Presence of the toxin in stool

Question 530

In a clinical specimen, the presence of sulfur granules strongly indicates the presence of which anaerobic bacterium?

A. Bacteroides fragilis
B. Actinomyces spp.
C. Fusobacterium nucleatum
D. Clostridium tetani

Answer 530

B. Actinomyces spp.

Question 532

The organism most commonly associated with otitis media infections is associated with which of the following positive test results?

A. Coagulase
B. VP
C. Optochin
D. Bacitracin

Answer 532

C. Optochin

Question 533

Which organism is most often responsible for impetigo?

A. Staphylococcus epidermidis
B. Streptococcus pyogenes
C. Enterococcus faecalis
D. Streptococcus agalactiae

Answer 533

B. Streptococcus pyogenes

Question 534

Which of the following is an example of an inappropriate specimen or condition that would warrant rejection for microbiology culture?

A. A nonsterile container for a stool culture
B. A swab of a skin and soft tissue infection
C. A tissue sample for anaerobic culture
D. A 24-hour urine sample for bacteriology culture

Answer 534

D. A 24-hour urine sample for bacteriology culture

Question 535

A patient with a Wood’s lamp–positive, dermatophytic infection has a skin scraping taken for culture. The organism grows on SDA agar with a light-tan front and salmon-colored reverse. Microscopically the organism produces rare distorted macroconidia and rare microconidia. Additionally, there was no growth on sterile rice media. What is the most likely organism?

A. Microsporum canis
B. Microsporum gypseum
C. Microsporum audouinii
D. Epidermophyton floccosum

Answer 535

C. Microsporum audouinii

Question 536

Which of the following is a key characteristic by which an unknown Cryptococcus spp. can be identified as Cryptococcus neoformans?

A. Appearance of yellow colonies
B. Positive urease test
C. Presence of a capsule
D. Positive niger seed agar test

Answer 536

D. Positive niger seed agar test

Question 537

A throat culture was taken from a 6-year-old boy with a gray pseudomembrane covering his oropharynx. A catalase-positive organism was isolated on cysteine-tellurite medium and subcultured to Tinsdale medium, where it grew as black colonies with brown halos. A Gram stain was performed on these colonies. Which of the following cellular morphologies was most likely seen?

A. Gram-positive branching bacilli
B. Gram-positive cocci in short chains
C. Gram-positive bacilli in irregular clublike shape
D. Gram-positive cocci in grapelike clusters

Answer 537

C. Gram-positive bacilli in irregular clublike shape

(C. diphtheriae - pseudomembranous formation - clublike morphology)

Question 538

Methylene blue remains ____ in the absence of oxygen (reduced) and turns ____ in the presence of oxygen:

a. Blue, white
b. White, blue
c. Pink, white
d. White, pink

Answer 538

b. White, blue

Question 539

A flexible calcium alginate nasopharyngeal swab is the collection device of choice for recovery of which organism from the nasopharynx?

A. Staph aureus
B. Strep pneumoniae
C. Corynebacterium diphtheriae
D. Bacteroides fragilis

Answer 539

C. Corynebacterium diphtheriae

Question 540

A vancomycin-resistant gram positive coccobacillus resembling the Streptococcus viridans group was isolated from the blood of a 42-year-old female patient undergoing a bone marrow transplant. The PYR and leucine aminopeptidase (LAP) tests were negative. The following results were noted:

Catalase =neg
Hip hydrolysis =neg
CAMP =neg
Esculin hydrolysis =neg
6.5% salt broth =neg
Gas from glucose =+

What is the correct identification?

A. Leuconostoc spp.
B. Enterococcus spp.
C. Staphylococcus spp.
D. Micrococcus spp.

Answer 540

A. Leuconostoc spp

Question 541

An immunocompromised patient with prior antibiotic treatment grew aerobic gram-positive cocci from several clinical specimens that were cultured. The organism was VANCOMYCIN RESISTANT and catalase negative. Additional testing proved negative for enterococci. What other groups of organisms might be responsible?

A. Leuconostoc spp. and Pediococcus spp.
B. Streptococcus pyogenes and Streptococcus agalactiae
C. Micrococcus spp. and Gemella spp.
D. Clostridium spp. and Streptococcus bovis

Answer 541

A. Leuconostoc spp. and Pediococcus spp.

Question 542

Specimens for virus culture should be transported in media containing:

A. Antibiotics and 5% sheep blood
B. Saline and 5% sheep blood
C. 22% bovine albumin
D. Antibiotics and nutrient

Answer 542

D. Antibiotics and nutrient

Question 543

In addition to chromosomal DNA, genes encoded in extrachromosomal genetic elements, such as PLASMIDS and TRANSPOSONS, may be transferred by:

A. Transformation
B. Transduction
C. Conjugation

Answer 543

C. Conjugation

Question 544

Recipient CELL UPTAKE OF NAKED (FREE) DNA released into the environment when another bacterial cell (i.e., donor) dies and undergoes lysis:

A. Transformation
B. Transduction
C. Conjugation

Answer 544

A. Transformation

Question 545

The process is mediated through viruses capable of infecting bacteria (BACTERIOPHAGES):

A. Transformation
B. Transduction
C. Conjugation

Answer 545

B. Transduction

Question 546

What is the number of bacteria needed to cause turbidity in broth culture and to be seen with an unaided eye?

A. 10^2 organisms
B. 10^4 organisms
C. 10^6 organisms
D. 10^8 organisms

Answer 546

C. 10^6 organisms

Question 547

When examining fluids by direct microscopic examination, if one organism is seen per oil immersion field, how many organisms per milliliter of specimen are present?

A. 5^5
B. 7^5
C. 15^5
D. 10^5

Answer 547

D. 10^5

Question 548

Currently, nucleic acid amplification testing (NAT) testing is performed to detect which viruses?

A. HIV and HTLV-I
B. HTLV I/II
C. HIV, HCV, and WNV
D. HIV, HBV, and WNV

Answer 548

C. HIV, HCV, and WNV

Question 549

The amount of antibiotic used in disk diffusion susceptibility testing is standardized and constant. Once the disk is placed on the inoculated plate and makes contact with the agar, the antibiotic in the disk begins to diffuse out. As it diffuses into the media, the concentration of antibiotic gets _____ the further it diffuses from the disk.

A. Lower
B. Higher
C. Variable
D. Cannot be determined

Answer 549

A. Lower

Question 550

Identification of Clostridium tetani is based upon:

A. Gram stain of the wound site
B. Anaerobic culture of the wound site
C. Blood culture results
D. Clinical findings

Answer 550

D. Clinical findings

Question 551

What are the optimal temperature and incubation time before a fungal blood culture is reported as negative?

A. 37°C; 21 days
B. 37°C; 7 days
C. 30°C; 21 days
D. 30°C; 7 days

Answer 551

C. 30°C; 21 days

Question 552

A dehydrated 25-year-old male patient was admitted to the hospital with symptoms similar to those of chronic fatigue syndrome. Serological testing proved negative for recent streptococcal infection, Epstein–Barr virus, and hepatitis. Which of the following viral serological tests should help with a possible diagnosis?

A. CMV
B. Echovirus
C. Respiratory syncytial virus
D. Measles virus

Answer 552

A. CMV

Question 553

In disk diffusion testing, zone diameters are too large or too small with all antimicrobials:

A. Check inoculum sizes
B. Obtain a fresh culture from an appropriate culture collection
C. Standardize illumination
D. Take a fresh culture from stock

Answer 553

A. Check inoculum sizes

Question 554

Chocolate agar contains:

A. Chocolate
B. Clotted blood
C. Brown nutrient agar
D. Hemolyzed red blood cells

Answer 554

D. Hemolyzed red blood cells

Question 555

Which organism is the most often recovered gram-positive cocci (catalase negative) from a series of blood cultures obtained from individuals with endocarditis?

A. Streptococcus agalactiae
B. Clostridium perfringens
C. Enterococcus faecalis
D. Pediococcus spp.

Answer 555

C. Enterococcus faecalis

Question 556

Which biochemical tests should be performed in order to identify colorless colonies growing on MacConkey agar (swarming colonies on blood agar) from a catheterized urine specimen?

A. Indole, phenylalanine deaminase, and urease
B. Glucose, oxidase, and lactose utilization
C. Phenylalanine deaminase and bile solubility
D. H2S and catalase

Answer 556

A. Indole, phenylalanine deaminase, and urease

Question 557

The use of 0.1% FUCHSIN substituted for safranin in the Gram-stain procedure may enhance the visibility of the organisms:

A. Bordetella spp.
B. Capnocytophaga spp.
C. Francisella spp.
D. Legionella spp.

Answer 557

D. Legionella spp.

Question 558

Anaerobic gram-negative rods were recovered from the blood of a patient after gallbladder surgery. The bacteria grew well on agar containing 20% bile, but were resistant to kanamycin and vancomycin. What is the most likely identification?

A. Clostridium perfringens
B. Bacteroides fragilis group
C. Prevotella spp.
D. Porphyromonas spp.

Answer 558

B. Bacteroides fragilis group