The most commonly isolated gram-positive cocci are best differentiated by their:
Gram stain morphology.
catalase reaction.
hemolytic reaction.
both a and b.
both b and c.
ANSWER:
(Level 1, Objective 1)
The novobiocin resistance test is used to
determine treatment options for Staphylococcus saprophyticus.
identify S. saprophyticus.
differentiate S. saprophyticus and S. hominis ssp. novobiosepticus.
both a and b.
ANSWER:
(Level 1, Objective 2)
The slide coagulase and the Staphylococcus latex agglutination tests are similar in that both test for the presence of
protein A.
free coagulase.
clumping factor.
thermonuclease.
ANSWER:
(Level 2, Objective 2)
The esculin/PYR disk test can be used to rapidly identify
Enterococcus spp.
Streptococcus pneumoniae.
Streptococcus pyogenes.
both a and b.
both a and c.
ANSWER:
(Level 1, Objective 2)
The optochin disk test is incubated at/in _____________________.
35°C, ambient air.
35°C, CO2.
42°C, CO2.
25°C, a capnophilic atmosphere.
ANSWER:
(Level 1, Objective 2)
A catalase-positive, gram-positive coccus that agglutinates in a slide coagulase test as well as in saline should be
reported as Staphylococcus aureus.
reported as Staphylococcus not S. aureus.
retested using another method.
retested for the catalase reaction.
ANSWER:
(Level 2, Objectives 2 and 3)
A positive rapid esculin test appears
dark.
pink.
red after the addition of the reagent.
blue.
ANSWER:
(Level 1, Objective 3)
Yellow colonies on mannitol salt agar indicate the definitive presence of
methicillin-resistant Staphylococcus aureus.
Staphylococcus aureus.
Staphylococcus not S. aureus.
unable to definitively identify.
ANSWER:
(Level 2, Objective 4)
A catalase-negative, gram-positive coccus that is bile esculin positive and 6.5% NaCl broth positive belongs to the Lancefield antigenic group
D.
C.
B.
A.
ANSWER:
(Level 2, Objective 5)
10. A leg wound isolate presents as a yellow pigmented, beta-hemolytic, catalase-positive, gram-positive cocci in clusters. Which of the following tests would you expect to be positive for this isolate?
Novobiocin resistance
Heat-stable thermonuclease
PYR
b and c
a and b
ANSWER:
(Level 2, Objective 5)
11. A catalase-negative coccus in pairs and short chains that is susceptible to ethyl hydrocupreine will also
a. require CO2 for growth.
b. be alpha hemolytic.
c. be bile soluble.
d. all of the above.
e. b and c.
ANSWER:
(Level 2, Objective 5)
12. The PBP2a latex agglutination test is used to detect catalase-positive, coagulase-positive, gram-positive cocci that are resistant to
a. vancomycin.
b. novobiocin.
c. oxacillin.
d. penicillin.
ANSWER:
(Level 2, Objective 6)
13. A catalase-negative, gram-positive coccus in chains that is positive for esculin and PYR hydrolysis is also vancomycin resistant. What additional antibiotic resistance can this organism exhibit?
a. high level aminoglycosides.
b. ampicillin and penicillin.
c. beta-lactamase production.
d. all of the above.
e. b and c.
ANSWER:
(Level 2, Objective 6)
14. An alpha-hemolytic, catalase-negative, gram-positive coccus that is susceptible to optochin can cause all of the following diseases except
a. pneumonia.
b. sinusitis.
c. meningitis.
d. pharyngitis.
ANSWER:
(Level 2, Objective 7)
15. The catalase-negative, gram-positive coccus that is the most common cause of neonatal sepsis and meningitis
a. has the potential to be vancomycin resistant.
b. hydrolyzes hippurate.
c. is susceptible to bacitracin.
d. is bile soluble.
ANSWER:
(Level 2, Objective 7)
16. Necrotizing fasciitis is caused by a
a. catalase-negative, gram-positive coccus that is susceptible to bacitracin.
b. catalase-negative, gram-positive coccus that produces CAMP factor.
c. catalase-positive, gram-positive coccus that produces coagulase.
d. catalase-positive, gram-positive coccus that is resistant to novobiocin.
ANSWER:
(Level 2, Objective 7)
17. Infections of indwelling devices, such as intravenous catheters, are often caused by catalase-positive, gram-positive cocci that are
a. coagulase positive and thermonuclease negative.
b. coagulase negative and novobiocin resistant.
c. caogulase positive and thermonuclease positive.
d. coagulase negative and novobiocin susceptible.
ANSWER:
(Level 2, Objective 7)
18. Which of the following factors accounts for the virulence of Streptococcus pyogenes?
a. âCâ substance
b. Protein A
c. M protein
d. mecA gene
ANSWER:
(Level 1, Objective 7)
19. The virulence factor most often associated with catalase-negative, gram-positive cocci that are bile soluble is
a. capsule production.
b. vancomycin resistance.
c. hyaluronidase.
d. streptolysin S.
ANSWER:
(Level 2, Objective 7)
20. A catalase-negative, alpha-hemolytic, gram-positive coccus that is resistant to ethyl hydrocupriene is usually considered
a. a member of the normal upper respiratory flora.
b. a pathogen in an expectorated sputum specimen.
c. the causative agent of non-suppurative sequelae.
d. a common urinary pathogen.
ANSWER:
(Level 2, Objective 8)
21. A catalase-positive, coagulase-negative, gram-positive coccus in clusters is isolated from the urine of a 24-year-old female. This isolate will require
a. additional testing to identify.
b. no further testing.
c. a screen for vancomycin resistance.
d. Lancefield grouping.
ANSWER:
(Level 2, Objective 10)
22. A blood culture yields yellow-pigmented, beta-hemolytic, catalase-positive, gram-positive cocci in clusters. The department is out of Staphylococcus latex agglutination reagent. The microbiologist sets up a tube coagulase and mannitol salt agar. She incubates both at 35°C in CO2 overnight. The next day the coagulase test is negative and the mannitol salt agar displays yellow colonies. How will you proceed with these results?
a. Report this organism as Staphylococcus aureus
b. Report this organism as Staphylococcus not S. aureus
c. Repeat the tests due to invalid results
d. Test the organism for novobiocin resistance
ANSWER:
(Level 3, Objective 10)
24. A patient, suspected to have bacterial endocarditis, had two sets of blood cultures drawn. All four bottles are positive with gram-positive cocci in pairs and chains. On sheep blood agar, the gray, transparent, alpha-hemolytic colonies are catalase negative, optochin resistant, ESC negative and PYR negative. Which of the following patient histories correlates with the presence of this organism?
a. 78-year-old male with bacterial pneumonia
b. 47-year-old female with a heart murmur and a history of dental surgery
c. 16-year-old female with a history of untreated pharyngitis
d. 3-day-old premature male
ANSWER:
(Level 3, Objective 10)
25. A translucent colony displaying subtle beta hemolysis is isolated from a placenta culture. The Gram stain revealed gram-positive cocci in pairs. The microbiologist drops 3% catalase reagent onto a colony on sheep blood agar, and it produces bubbles. He then performs a Staphyloccocus latex agglutination and the suspension remains smooth. The next step is to
a. report the organism as Staphylococcus not S. aureus.
b. report the organism as Staphylococcus aureus.
c. repeat the catalase test due to an invalid result.
d. perform a thermonuclease test due to an invalid latex agglutination result.
ANSWER:
(Level 3, Objective 10)
