10 exam-style questions with answers and explanations, straight from our 1,030-question bank. Tap an answer to check yourself. When you're ready, take the scored version in the free practice test.
The MMB exam has 305 questions and runs 6 hours 10 minutes.
These 10 free MMB questions are organized by exam domain, so you can see how each part of the Certification in Pathology: Medical Microbiology (MMB) blueprint is tested. Reveal the answer and explanation under each question.
During a routine blood-culture workup, a small gram-negative coccobacillus raises concern for Brucella. The isolate has already been manipulated on an open bench. No employee currently reports symptoms. What is the laboratory director's immediate priority?
Correct answer: A - Secure the isolate, stop further routine manipulation, and initiate a laboratory exposure assessment.
A positive blood-culture bottle tests positive for Staphylococcus aureus and mecA on a molecular panel that detects these targets independently and cannot assign mecA to a species in a mixed culture. Subculture yields both S. aureus and S. epidermidis. Neither isolate has undergone susceptibility testing. How should the laboratory finalize the methicillin-resistance interpretation for S. aureus?
Correct answer: C - Use validated cefoxitin or PBP2a testing on the pure S. aureus isolate to determine resistance.
A midstream urine specimen collected during preoperative assessment of a 71-year-old man produces 180 colonies of a single Escherichia coli isolate from a calibrated 0.001-mL loop. He has no urinary symptoms, fever, or catheter; urinalysis shows pyuria. He is scheduled for elective knee arthroplasty, not a urologic procedure. The surgeon asks whether to add an antibiotic course directed at the urine isolate, separate from routine surgical prophylaxis. Which response is appropriate?
Correct answer: D - 180,000 CFU/mL; asymptomatic bacteriuria does not warrant targeted urinary antibiotics in this setting.
Clarithromycin testing of a Mycobacterium abscessus subsp. abscessus respiratory isolate shows susceptibility at the initial read but resistance after incubation is extended to 14 days. The organism identification, inoculum, and quality-control results are acceptable. This time-dependent change most strongly supports which mechanism?
Correct answer: C - Inducible erm(41)-mediated methylation of 23S ribosomal RNA.
A Klebsiella pneumoniae bloodstream isolate carries NDM and CTX-M beta-lactamases and is resistant to aztreonam tested alone. In combination testing, adding avibactam markedly lowers the aztreonam MIC. Which interaction accounts for the restored activity?
Correct answer: D - Inhibition of the co-produced CTX-M serine beta-lactamase by avibactam.
Urgent sinus tissue from a patient with diabetic ketoacidosis and rapidly progressive facial pain shows vascular invasion by broad, irregularly contoured hyphae with sparse septation. Serum Aspergillus galactomannan and beta-D-glucan are negative. Which fungal group best fits the tissue findings despite the negative serum studies?
Correct answer: A - Mucorales
Admission screening at an acute-care hospital identifies Candida auris on an axilla-groin swab from a patient transferred after a stroke. The result is confirmed. The patient is afebrile, clinically stable, and has no evidence of invasive or other symptomatic C. auris infection. Which plan correctly separates transmission prevention from treatment?
Correct answer: A - Use Contact Precautions; do not prescribe antifungals for colonization alone.
A 12-day-old infant who did not pass the newborn hearing screen has a positive saliva CMV PCR. The saliva was collected 15 minutes after breastfeeding. The pediatrician wants confirmation that distinguishes congenital infection from breast-milk contamination of the specimen and later postnatal acquisition. Select the specimen-and-timing combination that best answers this question.
Correct answer: B - Collect urine now for CMV PCR, before the infant is 3 weeks old.
Three weeks after a possible sexual exposure, an adult presents with fever, pharyngitis, and a generalized rash. A laboratory HIV-1/2 antigen-antibody screening assay is repeatedly reactive, but the supplemental HIV-1/HIV-2 antibody differentiation assay is negative. The patient has not taken antiretroviral medication. Which test should resolve the discordance next?
Correct answer: C - Perform an HIV-1 RNA nucleic acid amplification test.
At a U.S. hospital, a thin blood smear from a febrile traveler confirms Plasmodium falciparum. Of 2,000 erythrocytes examined, 120 contain one asexual ring and 40 contain two asexual rings; the remaining cells are uninfected. The patient is alert and normotensive, with preserved renal function. Intravenous artesunate is immediately available. Which laboratory assessment and initial treatment recommendation are correct?
Correct answer: B - 8% parasitemia; start intravenous artesunate for severe malaria.
The MMB exam also covers these domains. Drill them in the full free practice test:
The full bank has 1,020 more MMB questions with explanations.
Continue in the free practice test →
View plans