American Society of Microbiology ABMM Sample Questions:

1. A microbiology laboratory is performing antimicrobial susceptibility testing using Etest strips. The MIC value is determined by:

A) The diameter of the zone of inhibition around the strip.
B) The presence or absence of growth at a single critical concentration.
C) The highest concentration that allows visible bacterial growth within the zone of inhibition.
D) The lowest concentration at which the elliptical zone of inhibition intersects the strip.

2. A traveler returning from Southeast Asia presents with fever, headache, and a maculopapular rash that started on the trunk and spread to the extremities, including the palms and soles. Serological testing is positive for Orientia tsutsugamushi. The vector responsible for transmitting this organism is a:

A) Tick
B) Mosquito
C) Flea
D) Mite (chigger)

3. A patient with a history of chronic lung disease develops a severe pneumonia. Bronchoalveolar lavage fluid reveals the presence of numerous cysts containing multiple nuclei, which stain positively with silver stains but poorly with Gram stain. The patient's CD4+ T-cell count is within the normal range. The MOST likely causative organism and the preferred treatment are:

A) Histoplasma capsulatum; amphotericin B followed by itraconazole.
B) Paragonimus westermani; praziquantel.
C) Pneumocystis jirovecii; trimethoprim-sulfamethoxazole.
D) Blastomyces dermatitidis; itraconazole.

4. A researcher is investigating the mechanism of action of a novel antibacterial agent that inhibits bacterial protein synthesis. The agent binds to the 50S ribosomal subunit and prevents the translocation of peptidyl- tRNA. This mechanism of action is similar to which of the following antibiotics?

A) Ciprofloxacin
B) Penicillin
C) Azithromycin
D) Vancomycin

5. Metagenomic analysis of a bronchoalveolar lavage (BAL) sample from a patient with severe pneumonia reveals a complex microbial community with a high abundance of both bacterial and fungal sequences. This approach is particularly useful in identifying:

A) The presence of specific virulence factors expressed by the identified pathogens.
B) The relative proportions of different immune cell populations in the BAL fluid.
C) The specific antibiotic susceptibility profile of the predominant bacterial pathogen.
D) The presence of fastidious or unculturable pathogens that may be missed by traditional methods.

Solutions: