Medical Technologist Test Microbiology 2 — Questions and Answers
Question 1: Which test detects the presence of bacterial DNA replication inhibition by an antibiotic?
- Kirby-Bauer disk diffusion
- E-test (epsilometer test)
- Broth microdilution MIC (Correct answer)
- Beta-lactamase assay
Correct answer: Broth microdilution MIC
Broth microdilution determines the minimum inhibitory concentration (MIC), quantifying the lowest drug concentration that inhibits visible bacterial growth.
Question 2: India ink preparation is used to detect which fungal pathogen in CSF?
- Candida albicans
- Aspergillus fumigatus
- Cryptococcus neoformans (Correct answer)
- Histoplasma capsulatum
Correct answer: Cryptococcus neoformans
India ink reveals the large polysaccharide capsule of Cryptococcus neoformans as a clear halo against a black background in CSF.
Question 3: Gram-positive cocci in clusters that are catalase-positive and coagulase-negative are MOST likely which genus?
- Streptococcus
- Staphylococcus epidermidis group (Correct answer)
- Enterococcus
- Bacillus
Correct answer: Staphylococcus epidermidis group
Coagulase-negative staphylococci (CoNS) like S. epidermidis are gram-positive cocci in clusters that are catalase-positive but coagulase-negative.
Question 4: CAMP test positivity is used to identify which pathogen?
- Listeria monocytogenes
- Streptococcus agalactiae (Group B Strep) (Correct answer)
- Clostridium perfringens
- Corynebacterium diphtheriae
Correct answer: Streptococcus agalactiae (Group B Strep)
Group B Streptococcus produces CAMP factor that enhances beta-lysin activity of S. aureus, creating an arrowhead hemolysis pattern.
Question 5: Antigenic variation is a major virulence mechanism of which sexually transmitted pathogen?
- Treponema pallidum
- Chlamydia trachomatis
- Neisseria gonorrhoeae (Correct answer)
- Haemophilus ducreyi
Correct answer: Neisseria gonorrhoeae
N. gonorrhoeae undergoes pilin antigenic variation, allowing it to evade the immune response and colonize mucosal surfaces persistently.
Question 6: Which culture medium is specifically used to isolate Bordetella pertussis?
- Thayer-Martin agar
- Regan-Lowe or Bordet-Gengou agar (Correct answer)
- BCYE agar
- CIN agar
Correct answer: Regan-Lowe or Bordet-Gengou agar
Bordetella pertussis requires Bordet-Gengou (charcoal horse blood) or Regan-Lowe agar for isolation due to its fastidious growth requirements.
Medical Technologist Test Microbiology 2
Which test detects the presence of bacterial DNA replication inhibition by an antibiotic?