Microbiology BOC Exam | Questions & Answers (100 %Score) Latest Updated 2024/2025
Comprehensive Questions A+ Graded Answers | With Expert Solutions
ASCP questions for the Naval MLT program
Questions by subject
1 - 89 Preanalytical and Susceptibility Testing
90 - 128 Aerobic Gram-Positive Cocci
129 - 202 Gram-Negative Bacilli
203 - 218 Aerobic Gram-Negative Cocci
219 - 227 Aerobic or Facultative Gram-Positive Bacilli
228 - 258 Anaerobes
259 - 303 Fungi
304 - 345 Mycobacteria
346 - 372 Viruses and Other Microorganisms
373 - 402 Parasite
Proper media for culture of a urethral discharge from a man include:
a sheep blood and phenylethyl alcohol agars b eosin-methylene blue and sheep blood agars
c thioglycollate broth and chocolate agar
d chocolate and modified Thayer-Martin agars - d chocolate and modified Thayer-Martin agars
d 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.
A sheep blood agar plate inoculated with 0.001mL of urine grows 70 colonies of Staphylococcus
aureus. How many colony forming units per mL of urine be reported?
a 70
b 700
c 7,000
d 70,000 - d 70,000
,d When 0.001 mL of urine is plated, the growth of one colony is equivalent to 1000 CFU/mL.
Thus 70 colonies is 70,000 CFU/mL.
The lowest concentration of antibiotic that inhibits growth of a test that inhibits growth of a test
organism is the:
a minimum inhibitory concentration
b serum inhibitory concentration
c minimum bactericidal titer
d maximum inhibitory titer - a minimum inhibitory concentration
a The MIC is a basic laboratory measurement of the activity of an antibiotic against an organism.
It is the lowest concentration of antibiotic that inhibits visible growth of the organism. It does not
represent the concentration of antibiotic that is lethal to the organism.
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 - b 10^3 CFU/mL
b Patients with infection often have at least 100,000 bacteria/mL of urine in the bladder.
However one third of young women with symptomatic cystitis have less than 100,000
bacteria/mL of urine. The Infectious Disease Society of America consensus definition of cystitis
is greater than or equal to 1,000 CFU/mL of a uropathogen.
The steam autoclave method of sterilization:
a uses 15 lbs of pressure for 15 minutes
b utilizes dry heat for 20 minutes
c produces a maximum temperature of 100 C
,d requires a source of ethylene oxide - a uses 15 lbs of pressure for 15 minutes
a The traditional gravity displacement steam sterilization cycle is 121°C for 15 minutes at 15
pounds per square inch. Ethylene oxide is an alternative sterilization method.
The expected colony count in a suprapubic urine from a healthy individual is:
a 0 CFU/mL
b 100 CFU/mL
c 1,000 CFU/mL
d 100,000 CFU/mL - a 0 CFU/mL
a Urine in the bladder is normally sterile. Suprapubic aspiration removes urine directly from the
bladder and yields a specimen free of urethral contamination.
An aspirate of a deep wound was plated on blood agar plates and incubated aerobically and
anaerobically. At 24 hours there was growth on both plates. This indicates that the organism is
a(n):
a nonfermenter
b obligate anaerobe
c aerobe
d facultative anaerobe - d facultative anaerobe
d Facultative anaerobes are organisms that can grow under both aerobic and anaerobic
conditions.
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
c Human blood contains substances 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 1:5-1:10. Dilutions less than this may cause the
blood to clot trapping organisms in the clot. Greater dilutions may increase the time to detection
A penicillin-resistant Neisseria gonorrhoeae produces:
a alpha-hemolysin
b beta-lactamase
c enterotoxin
d coagulase - b beta-lactamase
b Antimicrobial resistance in Neisseria gonorrhoeae is widespread. The production of beta-
lactamase (penicillinase) breaks open the beta lactam ring of penicillin, destroying its activity.
Thus, Ngonorrhoeae that produce beta lactamase are resistant to penicillin.
Which selective medium is used for the isolation of gram-positive microorganisms?
a Columbia CNA with 5% sheep blood
b trypticase soy agar with 5% sheep blood
c eosin methylene blue
d modified Thayer-Martin - a Columbia CNA with 5% sheep blood
a Columbia CNA agar contains colistin and nalidixic acid, which inhibit most gram-negative
organisms. Eosin methylene blue is selective and inhibits gram-positive organisms and modified
Thayer Martin is selective and inhibits gram-positive organisms, gram-negative bacilli and yeast.
The most sensitive substrate for the detection of beta-lactamases is:
a penicillin
b ampicillin
c cefoxitin
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