L1 MICRO Flashcards
Oxidase positive, urease negative:
A. B. pertussis
B. B. parapertussis
C. B. bronchiseptica
D. None of these
A. B. pertussis
Oxidase and urease positive:
A. B. pertussis
B. B. parapertussis
C. B. bronchiseptica
D. None of these
C. B. bronchiseptica
Oxidase negative, urease positive:
A. B. pertussis
B. B. parapertussis
C. B. bronchiseptica
D. None of these
B. B. parapertussis
Catalase positive, lactose negative, xylose positive:
A. Haemophilus aegypticus
B. Haemophilus ducreyi
C. Haemophilus parainfluenzae
D. Haemophilus influenzae
D. Haemophilus influenzae
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
C. Proteus sp.
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
C. Pasteurella multocida
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
D. Alcaligenes faecalis
Most often, are “dead-end” hosts.
A. Ticks
B. Mice
C. Sheep
D. Human
D. Human
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
A. #0.5 McFarland standard
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
C. 1% sulfuric acid and 1.175% barium chloride
Culture media for Vibrio spp., EXCEPT:
A. Buffered glycerol saline
B. Cary-Blair
C. Alkaline peptone water
D. Thiosulfate citrate bile salt (TCBS) agar
A. Buffered glycerol saline
Which one of the following is a prokaryote?
A. Bacteria
B. Algae
C. Protozoa
D. Fungi
E. Slime molds
A. Bacteria
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
C. Flagella
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
C. Calcium dipicolinate
Mycoplasma species lack which of the following components?
A. Ribosomes
B. Plasma membrane
C. Both DNA and RNA
D. Lipids
E. Peptidoglycan
E. Peptidoglycan
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
B. Decolorization using alcohol or acetone
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
C. N-glycolylmuramic acid and an increase in lipid content
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.
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B. Erysipelothrix sp.
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
D. Chocolate agar
Necrotizing fasciitis is a serious infection associated with:
A. Streptococcus agalactiae
B. Streptococcus mitis
C. Streptococcus pyogenes
D. Staphylococcus epidermidis
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C. Streptococcus pyogenes
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
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D. K/A
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
A. 0.01 or 0.001 mL of urine
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
S. agalactiae
B. Bacitracin, CAMP, PYR
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
S.aureus
B. Coagulase, glucose fermentation, DNase
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
S.pneumoniae
C. Optochin, bile solubility, PYR
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
C. Streptococcus pneumoniae
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
B. Gram-stained smear, catalase, and motility
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
A. Micrococcus
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
B. Micrococcus luteus
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
B. 5 μg of novobiocin
Which of the following organisms, to date, considered universally susceptible to penicillin?
A. Haemophilus influenzae
B. Neisseria gonorrhoeae
C. Streptococcus pyogenes
D. Corynebacterium diphtheriae
C. Streptococcus pyogenes
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
B. BSC Class II, A1
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
C. BSC Class II, B1
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
D. BSC Class II, B2
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
C. Vancomycin
The major toxicities of this antibiotic are RED MAN SYNDROME, nephrotoxicity, and ototoxicity:
A. Choramphenicol
B. Penicillin
C. Sulfonamide
D. Vancomycin
D. Vancomycin
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
D. 70,000
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
B. Minimum inhibitory concentration (MIC)
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
A. Minimum bactericidal concentration (MBC)
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
C. 1:10
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
C. Cation content of media
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
B. Decreased
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
B. Bacillus cereus
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
B. Klebsiella pneumoniae
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
A. It is oxidase positive.
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
C. Hippurate hydrolysis
A positive hippurate hydrolysis is a characteristic of:
A. Campylobacter coli
B. Campylobacter jejuni
C. Campylobacter lari
D. Campylobacter fetus
B. Campylobacter jejuni
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
C. Clostridium and Bacteroides spp.
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
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B. Proteus
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
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B. Corynebacterium diphtheriae
Yellow ground-glass colonies on cycloserine cefoxitin fructose agar (CCFA):
A. Bacillus anthracis
B. Bacillus cereus
C. Clostridium difficile
D. Clostridium perfringens
C. Clostridium difficile
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
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C. Bacillus cereus
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
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D. Nonhemolytic and nonmotile
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
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A. Liver cirrhosis
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
A. Haemophilus influenzae type b
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
S. pneumoniae
C. Optochin
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
C. Nasopharyngeal swab
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
A. Escherichia coli
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
C. Proteus mirabilis
Which Mycobacterium is associated with Crohn’s disease?
A. M. marinum
B. M. paratuberculosis
C. M. avium
D. M. gordonae
B. M. paratuberculosis
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
B. 240 Todd units
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
C. 320 Todd units
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
A. Brucella abortus
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
D. Brucella melitensis
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
C. Petragnani’s agar
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
C. H. haemolyticus
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
A. Niacin +, Nitrate reduction +, Photochromogen negative
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
A. Clostridium perfringens
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
B. Rejected
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
A. Yersinia enterocolitica
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
A. Indole, phenylalanine deaminase, and urease
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
A. Klebsiella oxytoca
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
B. Small, curved, motile gram-negative bacilli
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
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B. group B streptococci
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
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D. Charcoal particles
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
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A. 5% sheep blood agar
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
A. Guillain-Barré syndrome
Sulfur granules in a clinical specimen indicate the presence of:
A. Clostridium spp.
B. Fusobacterium spp.
C. Actinomyces spp.
D. Peptostreptococcus spp.
C. Actinomyces spp.
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
A. Micrococcus
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
B. Erysipelothrix
A negative PYR test is demonstrated by:
A. Enterococcus faecalis
B. Enterococcus faecium
C. Streptococcus pyogenes
D. Viridans streptococci
D. Viridans streptococci
Cystine-tellurite blood agar plates are recommended for the isolation of:
A. Corynebacterium diphtheriae
B. Streptococcus agalaciae
C. Streptococcus pyogenes
D. Group D streptococci
A. Corynebacterium diphtheriae
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
C. Francisella tularensis
Severe disseminated intravascular coagulation often complicates cases of septicemia caused by:
A. Acinetobacte rsp.
B. Moraxella sp.
C. Neisseria gonorrhoeae
D. Neisseria meningitidis
D. Neisseria meningitidis
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
C. Vibrio cholerae
The classic toxigenic strains of which serogroup are implicated in epidemic infections of Vibrio cholerae?
A. O1
B. O2
C. O3
D. O4
A. O1
A positive indole reaction is characteristic of:
A. Escherichia coli
B. Proteus mirabilis
C. Salmonella choleraesuis
D. Serratia marcescens
A. Escherichia coli
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
Oxidase Test
C. Moraxella catarrhalis
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
D. Moraxella catarrhalis
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
C. NALC-NaOH
Which one of the following drugs is NOT considered as primary antimycobacterial therapy?
A. Isoniazid
B. Kanamycin
C. Rifampin
D. Pyrazinamide
B. Kanamycin
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
A. Botulinum toxin
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%
C. 99.9%
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
B. 7.2 to 7.4
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
B. Bone marrow suppression and aplastic anemia
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
A. 10% ferric chloride
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
D. Alpha-naphthol and 40% KOH
In the RPR test, what is the gauge of the needle for antigen delivery?
A. 16
B. 18
C. 20
D. 21
C. 20
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
C. 180 rpm for 4 minutes
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
D. 180 rpm for 8 minutes
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
B. 100 rpm for 8 minutes
Most common cause of ASEPTIC MENINGITIS, an inflammation of the brain parenchyma:
A. Arenavirus
B. Cytomegalovirus
C. Enterovirus
D. Herpes simplex virus 2
C. Enterovirus
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)
D. Measles (rubeola)
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
D. C. albicans, C. dubliniensis
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
D. In vitro hair penetration by T. mentagrophytes
Added to SDA to inhibit most contaminating bacteria:
A. Dextrose
B. Chloramphenicol
C. Cycloheximide
D. Nystatin
B. Chloramphenicol
Added to SDA to inhibit saprophytic fungi:
A. Dextrose
B. Chloramphenicol
C. Cycloheximide
D. Nystatin
C. Cycloheximide
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
B. BSL-2 agents
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
D. BSL-4 agents
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
A. A. hydrophilia
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
B. M. microti
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
D. Pseudomonas aeruginosa
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
A. Burkholderia cepacia
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
A. Stenotrophomonas maltophilia
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
A. Lactobacilli
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
A. BSL-1
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
B. BSL-2
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
C. BSL-3
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
D. BSL-4
Which of the ff. makes Mannitol Salt Agar (MSA) selective?
A. Mannitol
B. Phenol red
C. Neutral red
D. Sodium chloride
D. Sodium chloride
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
D. Mycobacterium tuberculosis
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
A. M. avium-intracellulare complex
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
B. Chitin
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
A. Methyl red test
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
D. Voges-Proskauer test
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
D. Indole
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
A. β-Lactams and glycopeptides
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
A. Cephalosporins, penicillins, and aztreonam
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
B. Listeria monocytogenes
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
D. Erysipelothrix rhusiopathiae
The causative agent of plague is most often transmitted to humans by:
A. Fleas
B. Mosquitos
C. Dog bites
D. Inhalation
A. Fleas
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
A. Cytomegalovirus (CMV)
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
A. BK virus—urine
Kaposi sarcoma is associated with infection by:
A. Adenovirus
B. Cytomegalovirus
C. Hepatitis E virus
D. Human herpes virus 8
D. Human herpes virus 8
Which characteristic is most useful in differentiating Citrobacter and Salmonella?
A. H2S production
B. Indole production
C. Lysine decarboxylase
D. Urease production
C. Lysine decarboxylase
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
C. Histoplasma capsulatum
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
B. Sporothrix schenckii
The Epstein-Barr virus is associated with which of the following:
A. Chickenpox
B. Hodgkin lymphoma
C. Burkitt lymphoma
D. Smallpox
C. Burkitt lymphoma
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
B. 1 and 4
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
D. Culture specimens in ambient oxygen at 37C
Sensitivity testing commonly required, except:
A. Acinetobacter
B. Enterococci
C. Enterobacteriaceae
D. Listeria monocytogenes
D. Listeria monocytogenes
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
D. Catalysts that have become inactivated after repeated use
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
A. Pseudomonas aeruginosa
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
D. Acetone/ethanol
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
C. Lecithinase positive
Which of the following is the correct location of enteric “H” antigens?
A. Flagella
B. Capsule
C. Cell wall
D. Cytoplasm
A. Flagella
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
A. Guillain-Barré syndrome
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
B. Candida albicans
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
C. Tinsdale medium
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
B. Helicobacter pylori
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
A. Legionella pneumophila
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.
B. Bacteroides fragilis group
“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
C. Gardnerella vaginalis
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
D. Povidone–iodine
The indicator employed in TSI agar and urease test medium is:
A. Phenol red
B. Bromcresol purple
C. Bromthymol blue
D. Neutral red
A. Phenol red
The composition of optochin sensitivity test disk is:
A. 10% sodium desoxycholate
B. Bacitracin
C. Para-dimethylcinnamaldehyde
D. Ethylhydrocupreine hydrochloride
D. Ethylhydrocupreine hydrochloride
Plasma of choice for the coagulase test is:
A. Sheep plasma
B. Human plasma
C. Rabbit plasma
D. Rabbit serum
C. Rabbit plasma
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
B. Every week
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
B. Decreased
30% exhausted, 70% recirculated:
A. Class I
B. Class II A1
C. Class II B1
D. Class II B2
B. Class II A1
Sterile, screw-cap container tube, except:
A. Joint fluid
B. Sputum
C. Urine
D. Wound abscess
D. Wound abscess
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
D. Aspirate urine aseptically from the catheter tubing
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
D. Incubated at 37C and cultured as soon as possible
Growth in broth, except:
A. Diffuse
B. Flocculent
C. Pellicle
D. Turbid
A. Diffuse
Black belts dedicate ____ of their time to quality improvement projects, proactively addressing process and quality problems.
A. 10%
B. 20%
C. 70%
D. 100%
D. 100%
Green belts contribute ____ of their time to improvement projects while delivering their normal job functions.
A. 10%
B. 20%
C. 70%
D. 100%
B. 20%
Black belts
A. Project sponsors or champions
B. Project coaches or leaders
C. Project team members
D. Not traditionally used
B. Project coaches or leaders
Green belts
A. Project sponsors or champions
B. Project coaches or leaders
C. Project team members
D. Not traditionally used
C. Project team members
Blue belts
A. Project sponsors or champions
B. Project coaches or leaders
C. Project team members
D. Not traditionally used
A. Project sponsors or champions
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
C. Green
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
D. Black
Radioactive wastes or medical equipment contaminated or exposed in radioactivity:
A. Orange
B. Red
C. Green
D. Black
A. Orange
Pharmaceutical and chemical wastes:
A. Yellow
B. Yellow with black band
C. Red
D. Orange
B. Yellow with black band
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
A. Yellow
Component(s) of the chain of infection:
A. Susceptible host
B. Entry portal
C. Transmission of the pathogen
D. All of these
D. All of these
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
C. Hazard elimination
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
B. Non-latex gloves instead of latex gloves
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
A. Providing informed consent
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
C. Tubercular meningitis
Severe disseminated intravascular coagulation often complicates cases of septicemia caused by:
A. Acinetobacter sp.
B. Moraxella sp.
C. Neisseria gonorrhoeae
D. Neisseria meningitidis
D. Neisseria meningitidis
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
C. Streptococcus pneumoniae
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
D. It is an anaerobe
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
B. Fixation, crystal violet, iodine treatment, alcohol/acetone decolorization, safranin
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
D. All the cells will be red
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
B. Coxsackievirus A
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
B. Is highly contagious
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
A. Sexual partners of IV drug abusers who share needles
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
D. Measles virus
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
C. HBsAg
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
C. HCV
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
C. Pasteurella multocida
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
B. A foul-smelling discharge
Generally, wound exudates smell bad owing to production of organic acids by such anaerobes as B. fragilis.
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
D. Listeria monocytogenes
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
B. Clostridium difficile
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
A. Actinomyces israelii
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
B. Minimum inhibitory concentration (MIC)
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
A. Minimum bactericidal concentration (MBC)
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
C. Calcium and magnesium
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
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.
Transmission of Orientia tsutsugamushi is associated with what vector?
A. Ticks
B. Fleas
C. Lice
D. Chiggers
Bailey
D. Chiggers
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
D. Producing RNA from DNA
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
C. B-cell activation to produce antibodies
Most laboratories use which type of fire extinguisher?
A. Type A
B. Type B
C. Type C
D. Combination ABC
Bailey
D. Combination ABC
All of the following are differential media except:
A. Blood agar
B. Chocolate agar
C. MacConkey’s agar
D. Eosin methylene blue agar
Bailey
B. Chocolate agar
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
D. Acridine orange stain
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
D. Spirochetes such as Treponema pallidum
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
B. Beta hemolysis
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
C. 94 °C
The mechanism of action for tetracycline is inhibition of:
A. RNA synthesis
B. Cell wall synthesis
C. Protein synthesis
D. Membrane function
C. Protein synthesis
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
C. Modified Tinsdale
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
D. L. monocytogenes
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
A. Feta cheese
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
D. Mycetoma
Enterobacteriaceae are typically gram negative and:
A. Non–glucose fermenters
B. Capable of reducing nitrates to nitrites
C. Catalase negative
D. Oxidase positive
Bailey
B. Capable of reducing nitrates to nitrites
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
A. Cronobacter (Enterobacter) sakazakii
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
C. Phenylalanine deaminase and H2S
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
D. P. aeruginosa
The most common cause of hemolytic uremic syndrome is:
A. EPEC
B. EAEC
C. O157:NM
D. O157:H7
Bailey
D. O157:H7
Which E. coli produces a heat-labile (LT) enterotoxin and a heat-stable enterotoxin?
A. UPEC
B. ETEC
C. MNEC
D. EHEC
Bailey
B. ETEC
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
C. Stenotrophomonas sp.
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
A. Acinetobacter spp.
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
D. Moraxella catarrhalis
Into which genus have Haemophilus aphrophilus and Haemophilus paraphrophilus been recently reclassified?
A. Actinobacillus
B. Aggregatibacter
C. Haemophilus
D. Pasteurella
Bailey
B. Aggregatibacter
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
D. Aggregatibacter aphrophilus
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
D. A and C
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
C. H. ducreyi
Which encapsulated type of H. influenzae is most common?
A. Type a
B. Type b
C. Type c
D. Type d
Bailey
B. Type b
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
B. Small, curved, motile gram-negative bacilli
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
A. Guillain-Barré syndrome
A positive hippurate hydrolysis is a characteristic of:
A. Campylobacter coli
B. Campylobacter jejuni
C. Campylobacter lari
D. Campylobacter fetus
Bailey
B. Campylobacter jejuni
Campylobacter species should be grown at what optimum temperature?
A. 25° C
B. 37° C
C. 42° C
D. None of the above
C. 42° C
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
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.
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
B. Haverhill fever
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
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).
Bartonella quintana has been known to cause:
A. Carrion’s disease
B. Trench fever
C. Cat-scratch disease
D. Lyme disease
Bailey
B. Trench fever
What is the specimen of choice for culturing B. pertussis?
A. Throat
B. NP swab
C. Sputum
D. Anterior nose
Bailey
B. NP swab
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
B. Wild and laboratory rats
Sulfur granules in a clinical specimen indicate the presence of:
A. Clostridium spp.
B. Fusobacterium spp.
C. Actinomyces spp.
D. Peptostreptococcus spp.
Bailey
C. Actinomyces spp.
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
C. Mycobacterium avium complex
Which organism causes Rocky Mountain spotted fever?
A. Chlamydia trachomatis
B. Ehrlichia chaffeensis
C. Rickettsia rickettsii
D. Coxiella burnetii
Bailey
C. Rickettsia rickettsii
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
B. Chlamydia psittaci
Which serovar of Chlamydia trachomatis causes lymphogranuloma venereum?
A. A
B. C
C. H
D. L1
Bailey
D. L1
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
C. Fever, headache, and rash
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
B. In vitro hair perforation
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
D. C. albicans, C. dubliniensis
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)
C. M. tuberculosis
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
A. Mycobacterium tuberculosis
The genus of virus associated with anogenital warts, cervical dysplasia and neoplasia is:
A. Herpes simplex virus
B. Human papillomavirus
C. Cytomegalovirus
D. Coxsackievirus
B. Human papillomavirus
The Epstein-Barr virus is associated with which of the following:
A. Chickenpox
B. Hodgkin lymphoma
C. Burkitt lymphoma
D. Smallpox
C. Burkitt lymphoma
Which one of the following viruses is responsible for the most common congenital infection?
A. VZV
B. CMV
C. EBV
D. Adenovirus
B. CMV
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
C. Regan-Lowe agar
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
C. Sodium polyanethol sulfonate (SPS) and heparin
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
D. Urea breath test
Preanalytical (preexamination) variables in laboratory testing include:
A. Result accuracy
B. Report delivery to the ordering physician
C. Test turnaround time
D. Specimen acceptability
D. Specimen acceptability
Direct examination of the treponemes is most often performed by:
A. Light microscopy
B. Darkfield microscopy
C. VDRL testing
D. RPR testing
B. Darkfield microscopy
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
D. Marburg virus
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
A. Gram-negative bacteria
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
B. Corynebacterium diphtheriae
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
A. 0.01 or 0.001 mL of urine
Which of the ff. makes Mannitol Salt Agar (MSA) selective?
A. Mannitol
B. Phenol red
C. Neutral red
D. Sodium chloride
D. Sodium chloride
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
A. Class A
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
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.
The NPFA classification symbol contains information on all of the following except:
A. Fire hazards
B. Biohazards
C. Reactivity
D. Health hazards
Stras
B. Biohazards
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
A. Rescue persons in danger
Employees should not work with radioisotopes if they are:
A. Wearing contact lenses
B. Allergic to iodine
C. Sensitive to latex
D. Pregnant
Stras
D. Pregnant
Centrifuging an uncapped specimen may produce a biologic hazard in the form of:
A. Vectors
B. Sharps contamination
C. Aerosols
D. Specimen contamination
Stras
C. Aerosols
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
A. Urine specimen containers
The best way to break the chain of infection is:
A. Hand sanitizing
B. Personal protective equipment
C. Aerosol prevention
D. Decontamination
Stras
A. Hand sanitizing
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
A. BK virus—urine
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
A. Class I BSC
Which of these specimens is best for the detection of Pneumocystis jiroveci?
A. Bronchoalveolar lavage
B. Vaginal secretions
C. Bronchial washings
D. Amniotic fluid
A. Bronchoalveolar lavage
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
A. Induced sputum
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
D. Microbiology
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
C. 1.5 x 10^8 CFU/mL
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
A. 1 x 10^4 CFU/spot
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
D. 5 x 10^5 CFU/mL
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
C. Monitors patient samples day to day
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
B. Determine if the isolate is toxigenic by performing an Elek test
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
D. Staphylococcus aureus
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
D. Enterotoxin
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
D. Motility and beta-hemolysis on 5% sheep blood agar
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
D. Food
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
A. Oxidase test
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
C. Nucleic acid amplification
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
C. Bacteroides fragilis
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
A. Clostridium perfringens
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
B. Actinomyces spp.
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
C. Optochin
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
C. Urine
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
D. A 24-hour urine sample for bacteriology culture
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
B. Substances known or reasonably expected to contain pathogens
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
B. Aseptic meningitis
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
C. Cerebrospinal fluid Gram stain and culture
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
D. 5% sheep blood agar, chocolate agar, thioglycolate broth
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
A. These three antibiotic disks were outdated and had lost potency
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
B. Positive oxidase test
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
B. Salmonella enteritidis
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
A. Ammonia and CO2
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
C. Growth rate and colonial pigmentation
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
B. Demonstration of spore formation
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
B. Demonstration of spore formation
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
B. Streptococcus pyogenes
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
A. Staphylococcus aureus
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
A. Pseudomonas aeruginosa
Which of the following is a disinfectant?
A. Benzalkonium chloride
B. Chlorhexidine gluconate
C. Household bleach
D. Hydrogen peroxide
C. Household bleach
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
c. Emulsifier
Which of the following can specifically grow staphylococci?
- PEA
- Columbia CNA
- MSA
- BHI
a. 1,2,3,4
b. 1,2,3
c. 2,3,4
d. 1,3,4
a. 1,2,3,4
B-naphthylamine is the end product for which of the following Biochemical tests?
a. VP
b. Indole
c. PYR
d. Urease
d. Urease
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
d. Arbitrary primer PCR
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
c. Haemophilus aphrophilus will grow over the entire surface of the plate. X and V factors are required for growth.
The release of virions for influenza viruses is through ____
a. binary fission
b. budding
c. multiple fission
d. comp. cell destruction
c. multiple fission
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
b. H. capsulatum
What is the best stain for the sheath of Loa loa microfilariae?
a. Giemsa
b. Grunwald GIemsa
c. Delafield
d. Methylene blue
b. Grunwald GIemsa
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
d. Taxo A susceptible & FX resistant
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
c. N. subflava
Produces toxin except:
a. Neisseria
b. Clostridium
c. Escherichia
d. Salmonella
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
Outbreak of food poisoning leads to diarrhea in multiple patients. What should be done to investigate the cause of the outbreak?
Phage typing - detection of a single strain of bacteria
What is the purpose of flaming wired loops?
a. To prevent cross contamination
b. To sterilize
b. To sterilize
Priority: to avoid over inoculation
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
d. Hypochlorite
Amoeba that can survive harsh environments like chlorinated water but is killed at 70C
Naegleria fowleri and Acanthamoeba
Both Naegleri and Acanthamoeba can survive hot temperatures up to 60-65C
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
b. Biosafety cabinet
CSF
a. centrifuge
b. sediment
c. stain
d. culture
a. centrifuge
since this is the first thing to do
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
b. I, II, III, IV
Gastric aspirate - best specimen for infants
Nutritive media
a. MAC
b. CNA
c. Thioglycollate broth
d. BAP/CAP
d. BAP/CAP
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
B. RCF of 400 for 5 minutes
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
C. Gram stain
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
D. Acridine orange stain
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
B. 5% to 10% H2, 5% to 10% CO2, 80% to 90% N2, and 0% O2
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
C. 1% sulfuric acid and 1.175% barium chloride
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
A. #0.5 McFarland standard
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
A. Lactobacilli
SAFEST method to ensure that NO INFECTIVE MATERIALS REMAIN in samples or containers when disposed:
A. Autoclave
B. Incineration
C. Pasteurization
D. Filtration
B. Incineration
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
B. Minimum inhibitory concentration (MIC)
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
A. Minimum bactericidal concentration (MBC)
pH indicator incorporated in xylose-lysine-desoxycholate (XLD) agar:
A. Bromcresol purple
B. Bromthymol blue
C. Neutral red
D. Phenol red
D. Phenol red
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.
C. Micrococcus spp.
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
B. Micrococcus luteus
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.
B. Gemella spp.
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
A. BSL-1
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
B. BSL-2
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
C. BSL-3
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
D. BSL-4
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
B. BSC Class II, A1
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
C. BSC Class II, B1
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
D. BSC Class II, B2
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
C. Vancomycin
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
A. Alpha toxin
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
B. D-zone test
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
B. Erythromycin resistant, clindamycin sensitive
Resistance to clindamycin can be induced in vitro by
A. Ampicillin
B. Erythromycin
C. Gentamicin
D. Penicillin
B. Erythromycin
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
A. Brucella abortus
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
D. Brucella melitensis
Added to SDA to inhibit most contaminating bacteria:
A. Dextrose
B. Chloramphenicol
C. Cycloheximide
D. Nystatin
B. Chloramphenicol
Added to SDA to inhibit saprophytic fungi:
A. Dextrose
B. Chloramphenicol
C. Cycloheximide
D. Nystatin
C. Cycloheximide
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
B. Bacillus cereus
Fluorescence on Wood’s lamp, growth in rice medium:
A. Microsporum canis
B. Microsporum gypseum
C. Microsporum audouinii
D. Epidermophyton floccosum
A. Microsporum canis
Fluorescence on Wood’s lamp, no growth in rice medium:
A. Microsporum canis
B. Microsporum gypseum
C. Microsporum audouinii
D. Epidermophyton floccosum
C. Microsporum audouinii
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
C. Petragnani’s agar
Culture media for Vibrio spp., EXCEPT:
A. Buffered glycerol saline
B. Cary-Blair
C. Alkaline peptone water
D. Thiosulfate citrate bile salt (TCBS) agar
A. Buffered glycerol saline
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
C. 1.5 x 10^8 CFU/mL
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
A. 1 x 10^4 CFU/spot
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
D. 5 x 10^5 CFU/mL
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
C. 10^6 organisms
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
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.
An ammonia-like odor is characteristically associated with urine from patients with:
A. Phenylketonuria
B. Viral hepatitis
C. Bacterial infection
D. Yeast infection
C. Bacterial infection
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
C. Optochin
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
C. Syringe filled with pus, obtained before administration of antibiotics
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
A. Campylobacter jejuni
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
B. Rejected as unacceptable
Which of the following can be mistaken as myelin globules in sputum?
a. Blastomyces
b. Cryptococcus
c. Histoplasma
d. Candida
a. Blastomyces
Which of the following may resemble lymphocytes in CSF?
a. Blastomyces
b. Cryptococcus
c. Histoplasma
d. Candida
b. Cryptococcus
Larva in sputum:
a. Ascaris
b. Paragonimus
c. Both of these
d. None of these
a. Ascaris
ASH - larva
Paragonimus - egg in sputum
Ova (eggs) in sputum:
a. Ascaris
b. Paragonimus
c. Both of these
d. None of these
b. Paragonimus
ASH - larva in sputum
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
a. Pseudomonas
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
C. Microtube broth dilution
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
D. All of the above
Which of the following is the specimen of choice for detecting rotavirus?
A. Throat swab
B. Urine sample
C. Bronchoalveolar wash
D. Feces sample
D. Feces sample
Trophozoite forms of amoebae are found in what type of stool specimen?
A. Formed
B. Loose
C. Soft
D. Watery
D. Watery
More likely to contain trophozoites:
A. Liquid/diarrheic stool
B. Formed stool
C. Soft stool
D. None of these
A. Liquid/diarrheic stool
May contain trophozoites and cysts:
A. Liquid stool
B. Diarrheic stool
C. Formed stool
D. Soft stool
D. Soft stool
More likely to contain cysts (less likely to contain trophozoites)
A. Liquid stool
B. Diarrheic stool
C. Formed stool
D. Soft stool
C. Formed stool
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
D. Strongyloides stercoralis
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
D. Size of the genital primordium
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
B. Rhabditiform larvae
Infective stage is the SHEATHED FILARIFORM LARVA:
A. Strongyloides stercoralis
B. Ancylostoma duodenale, Necator americanus
C. Ascaris lumbricoides
D. Enterobius vermicularis
B. Ancylostoma duodenale, Necator americanus
Infective stage is the UNSHEATHED FILARIFORM LARVA:
A. Strongyloides stercoralis
B. Ancylostoma duodenale, Necator americanus
C. Ascaris lumbricoides
D. Enterobius vermicularis
A. Strongyloides stercoralis
Rhabditiform larva with hourglass-shaped esophagus and short buccal cavity:
A. Ascaris
B. Enterobius
C. Necator
D. Strongyloides
D. Strongyloides
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
B. Long buccal cavity, small genital primordium
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
C. Short buccal cavity, prominent genital primordium
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
D. S. stercoralis
The BAERMANN TECHNIQUE yields a good concentration of the living larvae of:
A. Angiostrongylus cantonensis
B. Brugia malayi
C. Enterobius vermicularis
D. Strongyloides stercoralis
D. Strongyloides stercoralis
Similar to hookworm eggs:
A. Ascaris
B. Trichuris
C. Trichostrongylus
D. Enterobius
C. Trichostrongylus
INTESTINAL NEMATODES
SMALL INTESTINES (CASH)
Capillaria
Ascaris
Strongyloides
Hookworms
& T.spiralis adult
INTESTINAL NEMATODES
LARGE INTESTINES (ET)
Enterobius
Trichuris
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
B. Eosinophils
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
B. Trichrome-stained smear
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
A. Central karyosome in the nucleus, ingestedRBCs, and clear pseudopodia
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
A. Short buccal capsule and large genital primordium
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
A. Taenia solium and Trichinella spiralis
An operculated cestode egg that can be recovered from human feces is:
A. Clonorchis sinensis
B. Diphyllobothrium latum
C. Paragonimus westermani
D. Dipylidium caninum
B. Diphyllobothrium latum
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
C. Either the definitive or the intermediate host
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
A. Modified Ziehl–Neelsen acid-fast stain
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
A. Giardia lamblia and Cryptosporidium spp.
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
C. Use of contaminated lens care solutions
Ingestion of which of the following EGGS will result in infection?
A. Strongyloides stercoralis
B. Schistosoma japonicum
C. Toxocara canis
D. Opisthorchis sinensis
C. Toxocara canis
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
D. Cyclospora cayetanensis oocysts
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
A. Light microscopy and modified trichrome stains
All of the following are differential media except:
A. Blood agar
B. Chocolate agar
C. MacConkey’s agar
D. Eosin methylene blue agar
B. Chocolate agar
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
D. Acridine orange stain
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
D. Chocolate agar
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
B. Beta hemolysis
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
C. Calcium and magnesium
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
A. 1 × 10^4 CFU/mL
A chromogenic cephalosporin is used to detect resistance to:
A. Macrolides
B. Aminoglycosides
C. β-lactams
D. Tetracyclines
C. β-lactams
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
A. 5% sheep blood agar
Necrotizing fasciitis is a serious infection associated with:
A. Streptococcus agalactiae
B. Streptococcus mitis
C. Streptococcus pyogenes
D. Staphylococcus epidermidis
C. Streptococcus pyogenes
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
B. Group B streptococci
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
A. Streptococcus pneumoniae from other alpha-hemolytic streptococci
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
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.
Pulmonary anthrax is also known as:
A. Black eschar
B. Woolsorters’ disease
C. Legionnaires’ disease
D. Plague
B. Woolsorters’ disease
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
D. Nonhemolytic and nonmotile
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
C. Bacillus cereus
It is a serious pathogen of the eye, causing progressive endophthalmitis:
A. Bacillus anthracis
B. Bacillus cereus
C. Bacillus subtilis
D. Bacillus thurigiensis
B. Bacillus cereus
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
A. Feta cheese
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
C. Modified Tinsdale
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
D. L. monocytogenes
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.
B. Erysipelothrix sp.
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
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).
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.
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).
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
D. Mycetoma
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.
A. Nocardia sp.
Which Nocardia sp. causes more than 80% of human infections?
A. N. asteroides
B. N. brasiliensis
C. N. otitidiscaviarum
D. N. farcina
A. N. asteroides
Incubation of which organism at 25°C produces a characteristic yellow pigment?
A. C. sakazakii
B. P. shigelloides
C. E. aerogenes
D. H. alvei
A. C. sakazakii
Enterobacteriaceae are typically gram negative and:
A. Non–glucose fermenters
B. Capable of reducing nitrates to nitrites
C. Catalase negative
D. Oxidase positive
B. Capable of reducing nitrates to nitrites
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
D. K/A
The most common cause of hemolytic uremic syndrome is:
A. EPEC
B. EAEC
C. O157:NM
D. O157:H7
D. O157:H7
Which E. coli produces a heat-labile (LT) enterotoxin and a heat-stable enterotoxin?
A. UPEC
B. ETEC
C. MNEC
D. EHEC
B. ETEC
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
C. Phenylalanine deaminase and H2S
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.
C. Stenotrophomonas sp.
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.
A. Acinetobacter spp.
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
D. P. aeruginosa
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
B. Pitting of the agar and a characteristic chlorine bleach smell
Into which genus have Haemophilus aphrophilus and Haemophilus paraphrophilus been recently reclassified?
A. Actinobacillus
B. Aggregatibacter
C. Haemophilus
D. Pasteurella
B. Aggregatibacter
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
A. Liver cirrhosis
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
C. H. ducreyi
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
D. Aggregatibacter aphrophilus
Which encapsulated type of H. influenzae is most common?
A. Type a
B. Type b
C. Type c
D. Type d
B. Type b
Bartonella quintana has been known to cause:
A. Carrion’s disease
B. Trench fever
C. Cat-scratch disease
D. Lyme disease
B. Trench fever
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
A. Guillain-Barré syndrome
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
A. Campylobacter jejuni
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
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.
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
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.
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
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.
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
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.
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
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.
Which type of microscope would be most useful in examining viruses and the structure of microbial cells?
Electron
Phase-contrast
Dark-field
Bright-field
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.
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
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.
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
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.
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
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).
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
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.
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
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
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
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.
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
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.
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
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
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
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.
Which of the following tests is used to monitor bactericidal activity during antimicrobic therapy in cases of endocarditis?
Elek
Tolerance
Sherris synergism
Schlichter
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.
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
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.
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
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.
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
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.
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
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.
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
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.
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
Causes one type of bacterial food poisoning
Staphylococcus aureus produces an enterotoxin that is associated with short incubation
food poisoning.
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
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.
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
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.
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
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.
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
Pulsed-field gel electrophoresis
The most commonly used method to determine the relatedness of 2 or more bacterial
strains is pulsed-field gel electrophoresis.
Specimens should be collected during the _______ of an illness and before
antibiotics are administered, if possible.
Acute phase
Chronic phase
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.
For wound specimen, wipe area with:
10% potassium hydroxide
70% alcohol
Formalin
Hydrogen peroxide
70% alcohol
CSF collected from a shunt:
BAP, MAC
BAP, CAP
CAP, MAC
BAP, CAP, THIO
BAP, CAP, THIO
CSF
BA, CA (Routine)
BA, CA, thio (Shunt)
Serum for serologic studies may be stored for up to 1 week:
4C
25C
37C
-20C
-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.
Blood agar is considered:
Nutritive medium
Selective medium
Differential medim
Nutritive and selective medium
Nutritive and differential medium
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.
Moderate growth; growth is out to the third quadrant:
1+
2+
3+
4+
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.
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
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.
Grows at the bottom of the thioglycollate broth:
Strict aerobes
Strict anaerobes
Microaerophilic organisms
Facultative anaerobes
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.
Grows near the surface of the thioglycollate broth:
Strict aerobes
Strict anaerobes
Microaerophilic organisms
Facultative anaerobes
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.
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
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.
In thioglycollate broth, these organisms will grow throughout the medium:
Strict aerobes
Strict anaerobes
Microaerophilic organisms
Facultative anaerobes
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.
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
Differential media
Interferes with folic acid pathway by binding the enzyme dihydropteroate synthase:
Aminoglycosides
Chloramphenicol
Penicillin
Sulfonamides
Sulfonamides
Monobactams:
Inhibits cell wall synthesis
Inhibits protein synthesis
Inhibits nucleic acid synthesis
Alters cell membrane
Inhibits cell wall synthesis
Bone marrow toxicity is the major side effect associated with:
Cephalosporin
Chloramphenicol
Penicillin
Sulfonamide
Chloramphenicol
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
1.5 x 10 8th CFU/mL
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
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.
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)
High (center of plate) to low (periphery of plate)
In disk diffusion susceptibility testing, as an antimicrobial agent diffuses
away from the disk, the concentration of antibiotic is:
Increased
Decreased
Unchanged
Inoculum dependent
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.
Differentiate clindamycin resistance among S. aureus:
Aminoglycoside screens
D zone test
Oxacillin agar screen
Vancomycin agar screen
D zone test
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
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.
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
Micrococcus luteus
Micrococcus is modified oxidase positive, bacitracin (0.04U) susceptible and resistant to
lysostaphin.
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
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).
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
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.
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
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).
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.
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.
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
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.
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
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.
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
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.
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
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.
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
Rejected
Specimens submitted for culture and recovery of any bacteria should be submitted without fixatives.
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
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.
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
Vancomycin
MRSA isolates are usually tested for susceptibility or resistance to vancomycin, a glycopeptide.
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
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.
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
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.
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
B. Lactic acid, mixed acids, alcohols, CO2 production
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
D. Conjugation
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
D. Staphylococcus aureus
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
D. Hektoen
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
A. Clumping factor
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
D. Coagulase test
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
D. Enterotoxin
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
A. Staphylococcus aureus
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
B. Listeria monocytogenes
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
A. Corynebacterium
(Corynebacterium - no spores but has metachromatic granules;)
nocardia - partially acid fast
MTB - acid fast
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
C. CAMP test, hydrogen sulfide production, esculin hydrolysis
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
B. Gram-stained smear, catalase, and motility
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
B. Demonstration of spore formation
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
C. M. leprae
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
C. Proteus mirabilis
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
B. Gram-negative diplococci
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
C. Nucleic acid amplification
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
A. Presence of the toxin in stool
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
B. Actinomyces spp.
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
C. Optochin
Which organism is most often responsible for impetigo?
A. Staphylococcus epidermidis
B. Streptococcus pyogenes
C. Enterococcus faecalis
D. Streptococcus agalactiae
B. Streptococcus pyogenes
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
D. A 24-hour urine sample for bacteriology culture
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
C. Microsporum audouinii
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
D. Positive niger seed agar test
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
C. Gram-positive bacilli in irregular clublike shape
(C. diphtheriae - pseudomembranous formation - clublike morphology)
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
b. White, blue
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
C. Corynebacterium diphtheriae
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.
A. Leuconostoc spp
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
A. Leuconostoc spp. and Pediococcus spp.
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
D. Antibiotics and nutrient
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
C. Conjugation
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
A. Transformation
The process is mediated through viruses capable of infecting bacteria (BACTERIOPHAGES):
A. Transformation
B. Transduction
C. Conjugation
B. Transduction
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
C. 10^6 organisms
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
D. 10^5
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
C. HIV, HCV, and WNV
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
A. Lower
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
D. Clinical findings
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
C. 30°C; 21 days
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
A. CMV
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
A. Check inoculum sizes
Chocolate agar contains:
A. Chocolate
B. Clotted blood
C. Brown nutrient agar
D. Hemolyzed red blood cells
D. Hemolyzed red blood cells
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.
C. Enterococcus faecalis
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
A. Indole, phenylalanine deaminase, and urease
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.
D. Legionella spp.
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.
B. Bacteroides fragilis group
