Practice test Lecture Flashcards
True about the Elek test except:
I. a test strip of filter paper containing diphtheria antitoxin is placed in the center of the
agar plate
II. presence of precipitin lines considered positive of diphtheria toxin
III. Filter paper impregnated with diphtheria antitoxin placed perpendicular to bacterial
streaks
IV. test to detect the toxigenicity of Corynebacterium species.
A. IV
B. I, III, IV
C. III
D. III, IV
A. IV
Rationale: di true yung IV kase dapat specific na corynebacterium diptheriae ang for elek test
Inhibit the beta-lysin property of Gram-positive cocci in clusters
A. Staphylokinase
B. CAMP factor
C. Lecithinase
D. Phospholipase D
Phospholipase D
Which of the bacterial classifications were based on differences at the end product of
metabolism, presence of specific antigen and colonial morphology?
A. subspecies
B. family
C. strain
D. genus
subspecies
A 28-year-old menstruating woman appeared in the emergency room with the following
signs and symptoms: fever, 104°F (40°C); VVBC, 16,000/uL; blood pressure, 90/65 mmHg a
scarlatiniform rash on her trunk, palms, and soles: extreme fatigue, vomiting and diarrhea.
The patient described in the case above most likely has
A. Staphylococcal food poisoning
B. Toxic shock syndrome
C. Scalded skin syndrome
D. Guillain-Barr syndrome
E. Chickenpox
Toxic shock syndrome
Which of the ff tests should be performed for initial differentiation of Listeria
monocytogenes from group B streptococci?
A. Gram stain, CAMP test, blackening at TSI
B. oxidase and bacitracin
C. Gram stain, motility at Room temp, catalase
D. Oxidase, CAMP test, glucose
Gram stain, motility at Room temp, catalase
Specimen for detection and diagnosis of diphtheria:
I. throat swab
II. nasopharyngeal swab
III. oropharyngeal swab
IV. bronchial aspirate
A. I, II, III, IV
B. I only
C. I, II, III
D. none of these
I, II, III
Drug of choice of the treatment of bacterial vaginosis
A. Erythromycin
B. Clindamycin
C. Penicillin
D. Metronidazole
Metronidazole
Which of the following is catalase negative?
I. Bacillus subtilis Listeria monocytogenes
II. Corynebacterium ulcerans, Erysipelothrix rhusopathiae
III. Streptococcus agalactiae, Neisseria baciliformis
IV. Neisseria elongate, Lactobacillus acidophilus
A. II, III, IV
B. III
C. I, II
D. III, IV
III, IV
Which of the following characteristics best describe a gram-positive bacterium?
I. periplasmic: present
II. Periplasmic: absent
III. Outer membrane: present
IV. Outer membrane: absent
A. I, IV
B. II, IV
C. II, III
D. I, II
II, IV
In identifying the presence of most group A β-hemolytic streptococci, versus those that are
non–group A, which of the following tests can be done?
A. PYR test, in which most non–group A β-hemolytic streptococci colonies would produce a bright red color after
addition of the PYR reagent to the filter paper
B. PYR test, in which most group A β-hemolytic streptococci colonies would produce a bright red color after
addition of the PYR reagent to the filter paper
C. Bile solubility test, in which most group A β-hemolytic streptococci colonies would be inhibited by an optochin
disk
D. Bile solubility test, in which most non–group A β-hemolytic streptococci colonies would be inhibited by an
optochin disk
B. PYR test
Rationale: in which most group A β-hemolytic streptococci colonies would produce a bright red color after addition of the PYR reagent to the filter paper
Which of the following is associated with infections in humans often linked to deli meats
and improperly pasteurized dairy products?
A. Bacillus cereus
B. Leuconostoc
C. Streptococcus agalactiae
D. Listeria monocytogenes
Listeria monocytogenes
Rationale: 3C chicken, cheese, coleslaw
A sputum sample from a patient with pneumonia produced many colonies of gramnegative diplococcic on chocolate plate that were also present in few numbers on Modified
Thayer-Martin after 48 hours. Given the results what is the most likely identification?
Catalase = positive Oxidase= positive
DNAse = positive
Tributyrin hydrolysis = positive Glucose = negative Sucrose = negative
Lactose = negative Maltose = negative Fructose =
negative
A. Neisseria sicca
B. Moraxella catarrhalis
C. Neisseria flavescens
D. Neisseria elongata
Moraxella catarrhalis
rationale: Moraxella lang yung nag iisa na negative sa lahat ng carbohydrate
An Old citizen club had their monthly picnic, half of them experienced onset of vomiting
after 6 -8 hours of eating pre-heated food. The most likely bacterial cause of such
symptom would be food poisoning caused by?
A. Bacillus anthracis
B. Staphylococcus aureus
C. Bacillus cereus
D. Listeria monocytogenes
Bacillus cereus
Rationale: keyword is preheat food, only bacillus spp can strive in high temperature, the answer should be cereus due to clinical manifestations of food poisoning
Colonies of Listeria monocytogenes on Sheep Blood Agar plate closely resembles the
colonies of?
A. Streptococcus agalactiae
B. Streptococcus bovis
C. Sreptococcus pyogenes
D. Streptococcus equisimilis
Streptococcus agalactiae
rationale: same sila na
narrow zone of ß hemolysis
In the CAMP test, a single streak of a beta-hemolytic Streptococcus is placed
perpendicular to a streak of beta-lysin producing Staphylococcus aureus. After the
incubation, a zone of increased lysis in the shape of an arrowhead is noted, this indicates
the presumptive identification of.
A. Group D enterococcus
B. Group B Beta-hemolytic streptococci
C. Group D Non-enterococcus
D. Group A Beta-hemolytic streptococci
Group B Beta-hemolytic streptococci
rationale: S. agalactiae yung may arrowhead sa CAMP
Identify the organism with the following biochemical reactions: Gram positive cocci in
pairs, Taxo P – resistant, Bile esculin test with blackening reaction, in 6.5% NaCl with
presence of turbidity, catalase without bubbles formation, PYRase with red color at the disk
and Bacitracin with no zone of inhibition.
A. Enterococcus
B. Group A Streptococci
C. Group D Non Enterococci
D. Group B Streptococci
Enterococcus
rationale: positive salt tolerance test and positive bile esculin
Which feature distinguishes Erysipelothrix rhusiopathiae from other clinically significant
non-spore-forming, gram positive, facultatively anaerobic bacilli?
A. Hydrogen sulfide production
B. more pronounced motility at 25C than 37C
C. end over end motility
D. Beta-hemolysis
Hydrogen sulfide production
Which of the anaerobic utilization of pyruvic acid was used by Gram positive cocci in
chains organism?
I. Mixed acid
II. Heterolactic
III. Homolactic
IV. Butyric Acid
A. II
B. I, IV
C. II, III
D. III
III only
rationale:
streptococcus and lactobacillus are gram positive organism, other choices have gram negtive or gram positive bacilli
A Gram’s stain of the CSF of a 33-year-old man revealed many polymorphonuclear
leukocytes and intra- and extra-cellular gram negative diplococcic. Culture and tests were
as follows: small, flat, gray colonies on chocolate agar, oxidase positive, Cystine trypticase
agar (CTA) maltose positive: CTA lactose negative. The most likely identity that isolate is:
A. Neisseria gonorrhoeae
B. Neisseria meningitidis
C. Moraxella catarrhalis
D. Acinetobacter species
Neisseria meningitidis
rartionale key word: maltose positive and polymorphonuclear
leukocytes and intra- and extra-cellular gram negative diplococcic.
Identify the organism with the following characteristics: Gram positive cocci, SXT-resistant, mucoid colony, Taxo A – 0mm , Taxo P - .17mm; Bile solubility: soluble; DNAse: no clearing
of colony; PYRase: colorless; CAMP: no arrow head formation; Hippurate hydrolysis: clear;
6.5 % Salt tolerance: cleared and Bile esculin: absence of blackening.
A. Streptococcus pneumoniae
B. Staphylococcus aureus
C. Streptococcus agalactiae
D. Streptococcus pyogenes
Streptococcus pneumoniae
rationale: unique test for identification of strep.pneumoniae
Solubility test - positive (soluble)
Taxo P test - susceptible
The Vogues- Proskauer test detects the production of:
A. p-dimethylaminobenzaldehyde
B. Decarboxylase activity
C. Acetylmethylcarbinol
D. phenylalanine
Acetylmethylcarbinol
Corynebacterium species recovered from a throat culture is considered a pathogen when it
produces:
A. pseudomembrane of the oropharynx
B. Tinsdale halo
C. an endotoxin
D. A & B
E. B & C
A & B
Which of the following microorganism is most likely to be isolated in cultures from the
anterior nares of the healthcare workers?
A. Streptococcus pneumoniae
B. Staphylococcus saprophyticus
C. Staphylococcus aureus
D. Bacillus cereus
Staphylococcus aureus
rationale: S.aureus are normal flora in anterior nares
Which of the following statements are CORRECT, except?
I. All prokaryotes are unicellular and multicellular.
II. All eukaryotes are unicellular and multicellular.
III. Peptidoglycan is present at all prokaryotes
IV. Polysaccharides are present at eukaryotes
A. I only
B. II, III, IV
C. I, III
D. II, IV
I, III
rationale:
Prokaryotes are only unicellular.
Eukaryotes can be multicellular and unicellular.
Not all prokaryotes have peptidoglycan.
Mycoplasma spp. and Ureaplasma spp. don’t have a peptidoglycan
Which of the following gram-negative diplococci causes endocarditis?
I. Neisseria sicca
II. Neisseria weaver
III. Neisseria bacilliformis
IV. Neisseria lactamica
A. I, IV
B. II, IV
C. II, III
D. I, III
I, III
Virulence factor causes severe type of skin localized infection.
I. Exotoxin A
II. Enterotoxin F
III. Epidermolytic toxin A
IV. Exopolysaccharide
A. I, III
B. III
C. I, III, IV
D. II, IV
I, III
rationale
I. Exotoxin A strep. pyogenes (scarlet fever)
II. Enterotoxin F superantigen (toxic shock syndrome)
III. Epidermolytic toxin A scalded skin syndrome
IV. Exopolysaccharide biofilm for medical devices causing prosthetic valve endocarditis
both scarlet fever and SSS may manifestation/symptoms na makikita sa skin
Encapsulated microorganism:
I. Neisseria meningitidis
II. Listeria monocytogenes
III. Streptococcus pneumoniae
IV. Bacillus anthracis
A. I, II, III
B. II, III
C. I, II, IV
D. I, III, IV
I, III, IV
Staining Technique of Lactophenol Cotton Blue
with result
fungal cell wall: blue
Staining Technique of Acridine Orange
with result
Nucleic acid: bright orange
Staining Technique of Calcofluor white
with result
fungal cell wall: apple green
Found in renal biopsy after the beta-hemolytic infection of:
A. Streptococcus pyogenes
B. Streptococcus agalactiae
C. Streptococcus pneumoniae
D. Staphylococcus aureus
Streptococcus pyogenes
A 52-year-old woman with a medical history of complicated urinary tract infection
readmitted due to high fever, severe chest pain, fatigue, aching joints and muscles and
difficult urination. Colorless colonies were isolated on MacConkey agar, positive on indole,
urease, citrate and malonate test. What is the possible microorganism?
A. Serratia marcescens
B. Citrobacter diversus
C. Escherichia coli
D. Proteus vulgaris
Proteus vulgaris
rationale: UTI was mentioned, the most common bacteria causing UTI are E.coli, Staphylococcus saprophyticus and Proteus spp
Which of the following is/are best to cultivate the Nocardia species?
I. 5-7 days of incubation at 37C
II. Incubate at room temperature
III. 3-6 days of incubation at 37C
IV. Use BCYE and Chocolate Agar Plate
III and IV
The following results are 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 =blue Motility = with turbidity at SIM
Glucose OF (open) = yellow Gelatin =liquefied
Pigment = green Arginine dihydrolase =purple
Growth at 42’C = positive Flagella = polar monotrichous
Which is the most likely organism?
A. Pseudomonas stutzeri
B. Pseudomonas pseudomallei
C. Pseudomonas aeruginosa
D. Pseudomonas cepacia
Pseudomonas aeruginosa
rationale: unique growth at 42’C
High fever and an inflammatory swelling of the axilla and groin lymph nodes are signs and
symptoms of 35-year-old female patient admitted at Emergency room. Four blood cultures were obtained, resulting in
growth of gram-negative bacilli resembling safety pins and showing colorless colonies on MacConkey Agar. Testing demonstrated a non-motile bacilli that was biochemically inert. What is the most likely identification?
A. Klebsiella oxytoca
B. Yersinia enterocolitica
C. Morganella morganii
D. Yersinia pestis
Yersinia pestis
rationale: resembling safety pins and non motile (Y.pestis the only non motile yersinia spp)
An isolate of Escherichia coli recovered from the stool of a patient with severe bloody
diarrhea should be tested for which carbohydrate before sending it to reference laboratory
for serological testing?
A. Raffinose
B. Mannitol
C. Sucrose
D. Sorbitol
Sorbitol
EHEC is colorless in SMAC
True about the cell wall of partially acid-fast bacilli, except:
I. contain shorter mycolic acid
II. peptidoglycan made up of mesodiaminopimelic acid
III. contain glucose and arabinose
IV. forms the filaments
III and IV
TRUE OR FALSE
Morse code appearance is seen in gram staining of Aggregatibacter actinomycetemcomitans
FALSE
rationale: should be bipolar staining
A curved gram-negative rod producing oxidase-positive colonies on blood agar
was recovered from a stool culture. Given the following results, what is the most
likely identification?
Lysine decarboxylase = positive Arginine decarboxylase = Negative
Indole = positive TSI = Alk/Acid
VP = Negative Lactose = Negative
Urease = variable String test = Negative
TCBS agar = Green colonies
A. Vibrio cholerae
B. Salmonella spp
C. Shigella spp
D. Vibrio parahaemolyticus
Vibrio parahaemolyticus
rationale: Stool culture - usually for vibrio spp
Vibrio cholerae - yellow in TCBS
Vibrio parahaemolyticus - Green colonies in TCBS
A 28-year-old female complained of a severe eye irritation after removing her softcontact lenses. Swab from the infected right eye was submitted in the microbiology
for culture and sensitivity. At 24 hours, growth of a gram-negative rod that tested
positive for cytochrome oxidase was noted. Bluish-green colonies were showed on
Mueller-Hinton Agar. What is the most likely microorganism?
A. Stenotrophomonas maltophilia
B. Burkholderia cepacia
C. Pseudomonas aeruginosa
D. Acinetobacter baumanii
Pseudomonas aeruginosa
RATIONALE Key word: Bluish-green colonies in MHA unique in aeruginosa
A catheterized urine specimen collected from a female patient who is residing in a nursing
home reveals the following:
TSI: K/A, no gas, H2S negative MacConkey: clear colonies
indole: red ring Citrate: blue
Motility: positive Urease: pink
Deaminase: burgundy
Identify the isolate:
A. Providencia stuartii
B. Klebsiella pneumoniae
C. Escherichia coli
D. Proteus mirabilis
E. Serratia marcescens
Providencia stuartii
rationale:
KEY word in question: Deaminase: burgundy only PPM are R/A in LIA choices left are providencia and protues but due to H2S result the probable answer is providencia
An acid fast organism is isolated form a wound culture taken from the hand of a marine
biology student The organism produces smooth, bright lemon-yellow colonies on
Lowenstein-Jensen agar when exposed to light The organism is negative for nitrate
reduction and is catalase and urease positive. The identity of this organism is:
A. Mycobacterium scrofulaceum
B. Mycobacterium tuberculosis
C. Mycobacterium fortuitum
D. Mycobacterium marinum
E. Mycobacterium ulcerans
Mycobacterium marinum
rationale key word: marine
biology student
Which of the following tests best differentiate Shigella species from E. coli?
A. Hydrogen sulfide, VP, citrate, and urea
B. Hydrogen sulfide, ME, citrate, and urea
C. Gas, citrate, and VP
D. Lactose, indole. ONPG; and motility
Lactose, indole. ONPG; and motility
Which of the following Mycobacterium species is diagnosed by biopsy other than culture?
A. M. bovis
B. M. leprae
C. M. avium
D. M. canetti
M. leprae
Which are the best two tests to differentiate Aeromonas hydrophilia from Plesiomonas
shigelloides?
A. DNase and VP
B. Growth on MacConkey and blood agar
C. Oxidase and motility
D. Indole and lysine decarboxylase
Growth on MacConkey and blood agar
1 Statement: All Non-fermentative Organisms are oxidase positive
2 Statement: Acinetobacter species is the negative in motility and oxidase.
A. Neither Statements are correct
B. 1 Statement is true, 2 Statement is true
C. 1 Statement is false, 2 Statement is true
D. 2 Statement is false, 1 Statement is true
C. 1 Statement is false, 2 Statement is true
A bloody stool cultured from a 35-year-old- woman after three days of severe diarrhea
showed the following results at 48 hours after being plated on the following media:
Mac Conkey agar: colorless colonies
Hektoen Enteric Agar: Blue-green colonies
Oxidase: colorless
Indole: colorless ring
SIM: No brush appearance from the stab line without H2S
Urease: Orange
ONPG: yellow
A. Escherichia coli
B. Salmonella cholerae- suis
C. Salmonella typhi
D. Shigella sonnei
Shigella sonnei
rationale: siya lang non motile sa choices
A wound sample was submitted at Microbiology reveals non-motile gram-variable bacilli,
aerobic and catalase positive. Identify the isolate:
A. Streptomyces anulatus
B. Gordonia bronchialis
C. Actinomadura madurae
D. Rhodococcus equi
Gordonia bronchialis
A gram-negative coccobacillus was isolated from an infected cat bite. The isolate grew on
blood agar with a musty smell, but did not grow on MacConkey agar. It was catalase,
indole, and oxidase positive and negative to urease. Which one of the following is the most
likely identity of this isolate?
A. Pasteurella multocida
B. Eikenella corrodens
C. Pasteurella canis
D. Pasteurella bettyae
Pasteurella multocida
Xylose lysine deoxycholate (XLD) agar is a highly selective medium used for the recovery
of which bacteria?
A. Yersinia species that do not grow on Hektoen Enteric Agar
B. Enterobacteriaceae from gastrointestinal specimens
C. Streptococcus species from stool cultures
D. Corynebacterium species from normal flora
Enterobacteriaceae from gastrointestinal specimens
TRUE OR FALSE
Rosette form is the microscopic morphology of Cardiobacterium hominis
TRUE
Grown inhibition by thiophene-2-carboxylic hydrazide (T2H) is used to differentiate
Mycobacterium tuberculosis from which otter Mycobacterium sp.?
A. M. avium complex
B. M. bovis
C. M. marinum
D. M. kansasii
M. bovis
Which test group best differentiates Acinetobacter species. from Pseudomonas.
aeruginosa?
A. Oxidase, motility, 42°C growth
B. MacConkey growth, 37C growth, catalase
C. Blood agar growth, oxidase, catalase
D. Oxidase, TSI, MacConkeY growth
Oxidase, motility, 42°C growth
A suspected case of plague requires which of the following procedures in order to confirm
Yersinia pestis?
I. Satellitism pattern in broth culture
II. Incubation of blood cultures at both 25°C and 30°C
III. Culture aspirates from buboes to MacConkey agar at room temperature
IV. safety pin appearance in leifson’s staining
A. II only
B. II, III
C. I, IV
D. II, III, IV
II only
pero nung sa exam ang naalala ko is walang 2 only na choices, nag 2 and 3 nalang ako
Which of the biochemical tests best to differentiate Klebsiella pneumoniae from Klebsiella
oxytoca?
A. Citrate
B. Indole
C. Urease
D. Sucrose
Indole
A gram negative, motile rod is isolated from a urine culture. On trypticase soy agar, the
organism produces red pigmented, DNAse positive colonies. Additional biochemical
testing revealed the following: KCN positive, ODC positive, ADC negative and LDC positive.
The most probable organism is:
A. Escherichia coli
B. Proteus vulgaris
C. Pseudomonas aeruginosa
D. Enterobacter cloacae
E. Serratia marcescens
Serratia marcescens
keyword: produces red pigmented
Which of the follow is noted for a positive result for niacin accumulation?
A. Mycobacterium gordonae
B. Mycobacterium fortuitum-chelonae
C. Mycobacterium tuberculosis
D. Mycobacterium avium-intracellulare
Mycobacterium tuberculosis
Colorless colonies on MacConkey Agar and yellow colonies on TCBS agar are
presumptive identification of Vibrio cholerae. Which biochemical tests would be
used to eliminate Aeromonas and Plesiomonas species in seafood food
poisoning?
I. Mannitol fermentation
II. String test
III. Gelatin Liquefaction
IV. Oxidase
A. II, IV
B. I, II
C. I, II, III
D. III, IV
I, II
Which of the following is the best media for the cultivation of Vibrio species?
A. TCBS, BAP, Alkaline Peptone Water
B. TCBS, BCYE, MacConkey, SSA
C. TCBS, Clary-Blair medium, SSA
D. TCBS, Alkaline Peptone Water, MacConkey
TCBS, Alkaline Peptone Water, MacConkey
88 -year- old diabetic patient, rushed to the emergency department with abdominal pain,
fever, vomiting, and nausea. A watery stool specimen producing no fecal leukocytes or
erythrocytes was cultured and grew a predominance of gram- negative fermentative bacilli.
The colonies were beta-hemolytic on Blood Agar Plate and colorless on Mac Conkey agar.
The colonies were both catalase and oxidase positive. What is the most likely
identification?
a. Shigella dysenteriae
b. Escherichia coli
c. Aeromonas hydrophilia
d. Salmonella species
Aeromonas hydrophilia
Smooth gray colonies showing no hemolysis are recovered from an infected cat scratch on
blood and chocolate agar but fail to grow on MacConkey agar. The organisms are gram negative pleomorphic rods that are both catalase and oxidase positive and strongly indole
positive. The most likely organism is:
a. Proteus spp.
b. Pasteurella spp.
c. Pseudomonas spp.
d. Capnocytophaga spp
Pasteurella spp.