©Jason MacConnell 2025 ALL RIGHTS RESERVED.
BOC Microbiology Exam Questions With
Correct Answers A+
Which of the following clean catch urine culture colony counts indicates the patient likely has a
urinary tract infection?
a. 10^1 CFU/mL
b. 10^3 CFU/mL
c. 10^5 CFU/mL
d. no growth - Answer✔b. 10^3 CFU/mL
The proper blood-to-broth ratio for blood cultures to reduce the antibacterial effect of serum in
adults is:
a. 1:2
b. 1:3
c. 1:10
d. 1:30 - Answer✔c. 1:10
The most sensitive substrate for the detection of beta-lactamases is:
a. penicillin
b. ampicillin
c. cefoxitin
d. nitrocefin - Answer✔d. nitrocefin
A Staphylococcus aureus isolate has an MIC of 4ug/mL to oxacillin. There is uncertainty as to
whether this represents an oxacillin (heteroresistant) resistant strain or a hyperproducer of beta-
lactamase.
Based on the below results for oxacillin and amoxicillin-clavulanic acid, which strain is
heteroresistant?
Strain Oxacillin Amoxicillin-clavulanic acid
Strain A susceptible susceptible
, ©Jason MacConnell 2025 ALL RIGHTS RESERVED.
Strain B susceptible resistant
Strain C resistant susceptible
Strain D resistant resistant - Answer✔d. Strain D: resistant to both Oxacillin and amoxicillin-
clavulanic acid
-Resistant to all beta-lactam agents and combinations
An Enterococcus isolated from multiple blood cultures in a patient endocarditis should be:
a. screened for high level aminoglycoside resistance
b. checked for tolerance
c. assayed for serum antimicrobial activity
d. tested for beta-lactamase production - Answer✔a. screened for high level aminoglycoside
resistance
The procedure that assures the most accurate detection of mecA-mediated oxacillin resistance in
routine broth microdilution susceptibility testing against S. aureus is:
a. addition of 4% NaCl
b. incubation at 30'C
c. incubation for 48 hours
d. use of cefoxitin for testing - Answer✔d. use of cefoxitin for testing
When performing a stool culture, a colony type typical of an enteric pathogen is subcultured on a
blood agar plate. The resulting pure culture is screened with several tests to obstain the following
results:
TSI: acid butt, alkaline slant, no gas, no H2S
Phenylalanine deaminase: negative
motility: positive
serological typing: Shigella flexneri (Shigella subgroup B)
The serological typing is verified with new kit and controls. The best course of action would be
to:
a. report the organism as Shigella flexneri without further testing
b. verify reactivity of motility medium with positive and negative controls
c. verify reactivity of the TSI slants with positive and negative controls for H2S production
d. verify reactivity of phenylalanine deaminase with positive and negative controls - Answer✔b.
verify reactivity of motility medium with positive and negative controls
, ©Jason MacConnell 2025 ALL RIGHTS RESERVED.
After satisfactory performance of daily disk diffusion susceptibility quality control is
documented, the frequency of quality control can be reduced to:
a. twice a week
b. every week
c. every other week
d. every month - Answer✔b. every week
Which of the following is the most appropriate specimen source and primary media bettery?
a. endocervical- chocolate, Martin Lewis
b. sputum- sheep blood, Thayer-Martin, KV-laked blood
c. CSF- Columbia CNA, MacConkey
d. urine- sheep blood, chocolate, Columbia CNA - Answer✔a. endocervical- chocolate, Martin
Lewis
The ONPG test allows organisms to be classified as a lactose fermenter by testing for which of
the following?
a. permease
b. beta-galactosidase
c. beta-actamase
d. phosphatase - Answer✔b. beta-galactosidase
Sodium bicarbonate and sodium citrate are components of which of the follwoing?
a. JEMBEC system
b. MTM agar
c. MYC medium
d. ML agar - Answer✔a. JEMBEC system
Chocolate agar base containing vancomycin, colistin, anisomycin, and trimethoprim is also
known as:
a. EMB agar
b. modified Thayer-Martin agar
c. Columbia CNA agar
d. Martin Lewis Agar - Answer✔d. Martin Lewis agar
- for Candida
, ©Jason MacConnell 2025 ALL RIGHTS RESERVED.
When evaluating a new susceptibility testing system, if the new system characterizes a
susceptible isolate as resistant, this is termed a:
a. very major error
b. major error
c. minor error
d. acceptable error - Answer✔b. major error
-Very major error: resistant isolate is characterized as susceptible
-major error: susceptible isolate characterized as resistant
-minor error: susceptible or resistant isolate characterized as intermediate or intermediate isolate
as susceptible or resistant
Which of the following methods is inadequate for the detection of vancomycin-intermediate S.
aureus?
a. broth macrodilution
b. agar dilution
c. gradient ddiffusion
d. disk diffusion - Answer✔d. disk diffusion
-Just wont work for vancomycin susceptibility for S aureus
First-generation cephalosporins can be adequately represented by:
a. cefotetan
b. ceftriaxone
c. cephalothin
d. cefoxitin - Answer✔c. cephalothin
Which one of the following organisms does not require susceptibility testing to the antimicrobial
indicated when isolated from a clinically significant source?
a. Staphylococcus aureus- clindamycin
b. Proteus mirabilis- gentamicin
c. Streptococcus pyogenes- penicillin
d. Escherichia coli- levofloxacin - Answer✔c. Streptococcus pyogenes- penicillin
-Resistance has not been documented
Which of the following antibiotics would routinely be tested and reported for isolates of
Pseudomonas aeruginosa?
BOC Microbiology Exam Questions With
Correct Answers A+
Which of the following clean catch urine culture colony counts indicates the patient likely has a
urinary tract infection?
a. 10^1 CFU/mL
b. 10^3 CFU/mL
c. 10^5 CFU/mL
d. no growth - Answer✔b. 10^3 CFU/mL
The proper blood-to-broth ratio for blood cultures to reduce the antibacterial effect of serum in
adults is:
a. 1:2
b. 1:3
c. 1:10
d. 1:30 - Answer✔c. 1:10
The most sensitive substrate for the detection of beta-lactamases is:
a. penicillin
b. ampicillin
c. cefoxitin
d. nitrocefin - Answer✔d. nitrocefin
A Staphylococcus aureus isolate has an MIC of 4ug/mL to oxacillin. There is uncertainty as to
whether this represents an oxacillin (heteroresistant) resistant strain or a hyperproducer of beta-
lactamase.
Based on the below results for oxacillin and amoxicillin-clavulanic acid, which strain is
heteroresistant?
Strain Oxacillin Amoxicillin-clavulanic acid
Strain A susceptible susceptible
, ©Jason MacConnell 2025 ALL RIGHTS RESERVED.
Strain B susceptible resistant
Strain C resistant susceptible
Strain D resistant resistant - Answer✔d. Strain D: resistant to both Oxacillin and amoxicillin-
clavulanic acid
-Resistant to all beta-lactam agents and combinations
An Enterococcus isolated from multiple blood cultures in a patient endocarditis should be:
a. screened for high level aminoglycoside resistance
b. checked for tolerance
c. assayed for serum antimicrobial activity
d. tested for beta-lactamase production - Answer✔a. screened for high level aminoglycoside
resistance
The procedure that assures the most accurate detection of mecA-mediated oxacillin resistance in
routine broth microdilution susceptibility testing against S. aureus is:
a. addition of 4% NaCl
b. incubation at 30'C
c. incubation for 48 hours
d. use of cefoxitin for testing - Answer✔d. use of cefoxitin for testing
When performing a stool culture, a colony type typical of an enteric pathogen is subcultured on a
blood agar plate. The resulting pure culture is screened with several tests to obstain the following
results:
TSI: acid butt, alkaline slant, no gas, no H2S
Phenylalanine deaminase: negative
motility: positive
serological typing: Shigella flexneri (Shigella subgroup B)
The serological typing is verified with new kit and controls. The best course of action would be
to:
a. report the organism as Shigella flexneri without further testing
b. verify reactivity of motility medium with positive and negative controls
c. verify reactivity of the TSI slants with positive and negative controls for H2S production
d. verify reactivity of phenylalanine deaminase with positive and negative controls - Answer✔b.
verify reactivity of motility medium with positive and negative controls
, ©Jason MacConnell 2025 ALL RIGHTS RESERVED.
After satisfactory performance of daily disk diffusion susceptibility quality control is
documented, the frequency of quality control can be reduced to:
a. twice a week
b. every week
c. every other week
d. every month - Answer✔b. every week
Which of the following is the most appropriate specimen source and primary media bettery?
a. endocervical- chocolate, Martin Lewis
b. sputum- sheep blood, Thayer-Martin, KV-laked blood
c. CSF- Columbia CNA, MacConkey
d. urine- sheep blood, chocolate, Columbia CNA - Answer✔a. endocervical- chocolate, Martin
Lewis
The ONPG test allows organisms to be classified as a lactose fermenter by testing for which of
the following?
a. permease
b. beta-galactosidase
c. beta-actamase
d. phosphatase - Answer✔b. beta-galactosidase
Sodium bicarbonate and sodium citrate are components of which of the follwoing?
a. JEMBEC system
b. MTM agar
c. MYC medium
d. ML agar - Answer✔a. JEMBEC system
Chocolate agar base containing vancomycin, colistin, anisomycin, and trimethoprim is also
known as:
a. EMB agar
b. modified Thayer-Martin agar
c. Columbia CNA agar
d. Martin Lewis Agar - Answer✔d. Martin Lewis agar
- for Candida
, ©Jason MacConnell 2025 ALL RIGHTS RESERVED.
When evaluating a new susceptibility testing system, if the new system characterizes a
susceptible isolate as resistant, this is termed a:
a. very major error
b. major error
c. minor error
d. acceptable error - Answer✔b. major error
-Very major error: resistant isolate is characterized as susceptible
-major error: susceptible isolate characterized as resistant
-minor error: susceptible or resistant isolate characterized as intermediate or intermediate isolate
as susceptible or resistant
Which of the following methods is inadequate for the detection of vancomycin-intermediate S.
aureus?
a. broth macrodilution
b. agar dilution
c. gradient ddiffusion
d. disk diffusion - Answer✔d. disk diffusion
-Just wont work for vancomycin susceptibility for S aureus
First-generation cephalosporins can be adequately represented by:
a. cefotetan
b. ceftriaxone
c. cephalothin
d. cefoxitin - Answer✔c. cephalothin
Which one of the following organisms does not require susceptibility testing to the antimicrobial
indicated when isolated from a clinically significant source?
a. Staphylococcus aureus- clindamycin
b. Proteus mirabilis- gentamicin
c. Streptococcus pyogenes- penicillin
d. Escherichia coli- levofloxacin - Answer✔c. Streptococcus pyogenes- penicillin
-Resistance has not been documented
Which of the following antibiotics would routinely be tested and reported for isolates of
Pseudomonas aeruginosa?
