Free D(ABMM) Practice Questions

Question 1

A positive blood-culture bottle yields Staphylococcus aureus and Staphylococcus epidermidis. A multiplex assay detects both organisms and mecA using separate organism and resistance-gene targets; it has no target linking mecA specifically to S. aureus. Both species grow on subculture, but isolate susceptibility results are pending. Which interpretation can the director report from the molecular findings?

Accepted Answer

Species assignment of the methicillin-resistance determinant remains unresolved.

Answer

Both staphylococcal species carry a methicillin-resistance determinant.

Answer

MRSA is established because S. aureus and mecA are both detected.

Answer

Only S. epidermidis is methicillin resistant; S. aureus remains provisionally susceptible.

Question 2

An 18-day-old infant referred after an abnormal newborn hearing screen has a positive saliva cytomegalovirus (CMV) PCR. The sample was collected 10 minutes after breastfeeding. Infant CMV IgG is positive and IgM is negative. To establish whether congenital infection is present, the confirmation specimen to request now is:

Accepted Answer

Urine for CMV PCR collected at the current visit

Answer

Infant serum for repeat CMV IgM testing at the current visit

Answer

Saliva for CMV PCR collected at 1 month of age, away from feeding

Answer

Maternal serum for CMV IgG testing alongside the infant serum result

Question 3

In a 24-specimen molecular run, the external positive and negative controls pass. One patient specimen has neither pathogen-target amplification nor amplification of the internal control required for a valid negative result. The other 23 reactions meet all acceptance criteria. Reactions are independently controlled, and there is no evidence of a shared processing failure. What should be released from this run?

Accepted Answer

Release the 23 valid results; repeat the invalid specimen using the assay's validated procedure.

Answer

Report every target-negative result because the external positive and negative controls pass.

Answer

Report the affected specimen as negative with an inhibition warning, and release the other 23 results.

Answer

Withhold all 24 results and repeat the run, since one failed internal control invalidates the entire batch.

Question 4

Urine Histoplasma and Blastomyces antigen assays are both positive in a patient with pulmonary nodules and a persistent skin lesion. Biopsy of the lesion shows thick-walled yeasts with broad-based buds; fungal culture is pending. Which conclusion best reconciles the tissue and antigen results?

Accepted Answer

Blastomyces infection is favored; cross-reactivity can account for the positive Histoplasma antigen result.

Answer

Concurrent histoplasmosis and blastomycosis are established by the two antigen results.

Answer

Histoplasma infection is favored because broad-based buds identify its tissue form.

Answer

Past exposure explains both antigen results; the skin lesion represents an unrelated process.

Question 5

Eight years ago, an immunocompetent technologist completed hepatitis B vaccination and had anti-HBs of 68 mIU/mL six weeks after the final dose. Today, the technologist sustains a needlestick from an HBsAg-positive patient; a newly ordered anti-HBs level is 4 mIU/mL. Wound care, exposure reporting, and assessment for other bloodborne pathogens are underway. What HBV-specific prophylaxis does this history warrant?

Accepted Answer

Neither HBIG nor additional vaccine is indicated; the documented response establishes protection in this immunocompetent worker.

Answer

One vaccine booster without HBIG, to restore the anti-HBs concentration to at least 10 mIU/mL.

Answer

One dose of HBIG plus a repeat vaccine series, given exposure to an HBsAg-positive source.

Answer

Two HBIG doses one month apart, treating the current antibody result as evidence of vaccine nonresponse.

Question 6

For a new respiratory NAAT, a laboratory compares 200 specimens with a routine NAAT that is not a reference standard. The new assay detects 96 of the 120 comparator-positive specimens and is positive in 4 of the 80 comparator-negative specimens. No independent assessment of infection status is available. Which quantitative statement is supportable?

Accepted Answer

Positive percent agreement with the comparator is 80%; the study does not establish clinical sensitivity.

Answer

Clinical sensitivity is 80%, using comparator positivity to define which patients truly have the infection.

Answer

Positive percent agreement is 86%, incorporating specimens negative by both assays.

Answer

Positive predictive value is 96%, because comparator confirmation establishes infection in 96 of the 100 new-assay positives.

Question 7

During spontaneous labor at 39 weeks, the obstetric team reviews a negative vaginal-rectal group B Streptococcus (GBS) culture obtained at 36 weeks. At 16 weeks, a properly collected urine culture had grown GBS at 1,000 CFU/mL without urinary symptoms. The team asks whether prophylaxis is still indicated. Which interpretation should govern intrapartum care?

Accepted Answer

Give intrapartum prophylaxis because GBS bacteriuria in this pregnancy remains an indication.

Answer

Withhold prophylaxis because the later negative vaginal-rectal culture supersedes the urine result.

Answer

Give prophylaxis only if a urine culture collected during labor again recovers GBS.

Answer

Withhold prophylaxis because the low asymptomatic urine count never met the treatment threshold.

Question 8

Routine testing of a pure Staphylococcus aureus isolate gives erythromycin resistance and apparent clindamycin susceptibility. On a properly performed disk induction test, the clindamycin zone flattens on the side facing the erythromycin disk. Growth and quality controls are acceptable. The final clindamycin report should read:

Accepted Answer

Resistant; the positive induction test overrides the initial susceptible category.

Answer

Susceptible; clindamycin remains usable if erythromycin is not administered with it.

Answer

Intermediate; the conflicting phenotypic results require an intermediate susceptibility category.

Answer

Pending; clindamycin resistance cannot be reported until an erm gene is confirmed by molecular testing.

Question 9

An unidentified yeast in an active proficiency-testing event reaches the end of the laboratory's routine in-house workup. A patient isolate at this point would be sent to a reference laboratory. The proficiency-testing reporting deadline is still open. CLIA permits the laboratory to:

Accepted Answer

Submit the findings obtained in-house without referring the proficiency-testing isolate.

Answer

Refer the isolate to its usual reference laboratory, following the written procedure used for patient specimens.

Answer

Consult another laboratory in the hospital network about its identification data without transferring the physical isolate.

Answer

Use a research identification method unavailable in routine patient testing to obtain a species-level answer before submission.

Question 10

Reference testing of a pretreatment Mycobacterium tuberculosis-complex isolate reports resistance to isoniazid, rifampin, levofloxacin, and amikacin, with susceptibility to bedaquiline and linezolid. All results are valid. Under current WHO definitions, the most specific drug-resistance category supported by this profile is:

Accepted Answer

Pre-extensively drug-resistant tuberculosis (pre-XDR-TB)

Answer

Rifampicin-resistant tuberculosis (RR-TB)

Answer

Multidrug-resistant tuberculosis (MDR-TB)

Answer

Extensively drug-resistant tuberculosis (XDR-TB)

Free D(ABMM) Practice Questions

Domain 1: Directing Laboratory Testing Functions 44.5% of exam

Question 1

Question 2

Question 3

Question 4

Question 5

Domain 2: Directing Laboratory Administrative Functions 19% of exam

Question 6

Question 7

Domain 3: Ensuring Safety and Security in the Laboratory 11.5% of exam

Question 8

Domain 4: Consulting with Other Medical Professionals 25% of exam

Question 9

Question 10

That's 10 of 1,030