ABMM (ABMM) Free Practice Test

Question 1

A clinical isolate of Klebsiella pneumoniae from a patient with a refractory urinary tract infection exhibits resistance to carbapenems (imipenem, meropenem, ertapenem). PCR analysis reveals the presence of the blaKPC gene. Which of the following enzymatic mechanisms is responsible for this resistance?

A. Modification of the ribosomal target site, preventing antibiotic binding.

B. Hydrolysis of the beta-lactam ring, leading to an inactive antibiotic derivative.

C. Efflux of the carbapenem antibiotic out of the bacterial cell.

D. Trapping of the carbapenem molecule by a decoy protein.

Correct Answer: B

Question 2

Microscopic examination of a potassium hydroxide (KOH) preparation of skin scrapings from a patient with tinea versicolor typically reveals:

A. Broad, aseptate hyphae with sporangiophores

B. Septate hyphae and arthroconidia

C. Cigar-shaped yeast cells

D. Short, unbranched hyphae and globose yeast cells in clusters ("spaghetti and meatballs")

Correct Answer: D

Question 3

What is considered the "gold standard" for routine monitoring of the lethality of steam sterilization (autoclave) cycles in healthcare facilities?

A. Performing a Bowie-Dick test at the beginning of each day for pre-vacuum sterilizers.

B. Regular use of biological indicators containing spores of Geobacillus stearothermophilus.

C. Use of chemical indicator strips placed inside each sterilized pack.

D. Daily check of autoclave cycle printouts for correct time, temperature, and pressure.

Correct Answer: B

Question 4

A patient presents with a pruritic rash consisting of raised, serpiginous tracks on their skin. The patient recently returned from a Caribbean vacation and reported walking barefoot on the beach. The MOST likely causative organism is:

A. Sarcoptes scabiei

B. Larvae of Ancylostoma braziliense

C. Pediculus humanus

D. Larvae of Strongyloides stercoralis

Correct Answer: B

Question 5

A clinical microbiology laboratory is implementing a new laboratory information system (LIS). A critical step in the validation process is ensuring the accurate and reliable transfer of data, including patient demographics, test orders, and results. This aspect of validation primarily focuses on:

A. Workflow efficiency and user training.

B. Clinical sensitivity and specificity.

C. Data integrity and interoperability.

D. Analytical sensitivity and specificity.

Correct Answer: C

Question 6

During a community outbreak of influenza, a public health laboratory performs rapid antigen testing on nasopharyngeal swabs. A test for influenza A is positive, but the influenza B test is negative. Subsequently, RT-PCR is performed on the same sample, and it is negative for both influenza A and B viral RNA. The MOST likely explanation for this discordant result is:

A. The rapid antigen test has low sensitivity, resulting in a false positive.

B. The rapid antigen test yielded a false positive result, and the RT-PCR was a true negative.

C. The RT-PCR assay has a high limit of detection, missing a low viral load.

D. The patient was infected with a novel influenza strain not detected by either assay.

Correct Answer: B

Question 7

A patient develops a severe skin infection after a puncture wound sustained while gardening. Culture of the wound exudate grows a Gram-positive, spore-forming bacillus that is anaerobic and produces a potent neurotoxin causing sustained muscle contraction. The MOST likely organism is:

A. Clostridium tetani

B. Bacillus anthracis

C. Clostridium botulinum

D. Clostridium perfringens

Correct Answer: A

Question 8

A patient develops severe, watery diarrhea shortly after starting a course of clindamycin. Stool testing using a cytotoxicity assay is positive. This result is most consistent with infection by which organism?

A. Clostridioides difficile

B. Norovirus

C. Giardia lamblia

D. Campylobacter jejuni

Correct Answer: A

Question 9

Clavulanic acid is often combined with amoxicillin (e.g., Augmentin™) to overcome certain types of bacterial resistance. What is the primary mechanism by which clavulanic acid enhances amoxicillin's activity?

A. It functions as a potent, irreversible inhibitor of many bacterial beta-lactamase enzymes.

B. It inhibits bacterial efflux pumps that would otherwise remove amoxicillin from the cell.

C. It increases the outer membrane permeability to amoxicillin in Gram-negative bacteria.

D. It binds to alternative penicillin-binding proteins (PBPs), providing a synergistic bactericidal effect.

Correct Answer: A

Question 10

Which serological marker pattern is most consistent with chronic Hepatitis B virus infection with high infectivity?

A. HBsAg (-), Anti-HBs (+), Anti-HBc Total (+), IgM Anti-HBc (-), HBeAg (-), Anti-HBe (+)

B. HBsAg (+), Anti-HBs (-), Anti-HBc Total (+), IgM Anti-HBc (+), HBeAg (+), Anti-HBe (-)

C. HBsAg (-), Anti-HBs (+), Anti-HBc Total (-), IgM Anti-HBc (-), HBeAg (-), Anti-HBe (-)

D. HBsAg (+), Anti-HBs (-), Anti-HBc Total (+), IgM Anti-HBc (-), HBeAg (+), Anti-HBe (-)

Correct Answer: D

Question 11

Which of the following viruses is an enveloped, double-stranded DNA virus known to cause latent infections often reactivated during immunosuppression?

A. Rotavirus

B. Poliovirus

C. Influenza A virus

D. Cytomegalovirus (CMV)

Correct Answer: D

Question 12

A clinical microbiology laboratory is monitoring the emergence of antimicrobial resistance. The detection of a bacterial isolate with reduced susceptibility to multiple classes of antibiotics, often due to horizontal gene transfer of resistance determinants, is characteristic of:

A. A multidrug-resistant (MDR) organism.

B. An intrinsically resistant organism.

C. A pan-susceptible organism.

D. A naturally competent organism.

Correct Answer: A

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American Society of Microbiology ABMM (ABMM) Free Practice Test