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Pulmonary tuberculosis — USMLE Step 2 CK MCQ

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HardInternal MedicinePulmonary tuberculosisUSMLE Step 2 CK

A 39-year-old man recently arrived from a region with high tuberculosis prevalence. He has 6 weeks of cough, weight loss, night sweats, and an upper-lobe cavitary opacity. He is hemodynamically stable and can produce sputum. Which initial diagnostic and infection-control plan is most appropriate?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: C — Use airborne isolation; obtain three sputums for smear and culture plus one molecular assay

Explanation lettering: E = shown as A · A = shown as B · D = shown as C · C = shown as D · B = shown as E

D is correct: suspected infectious pulmonary tuberculosis requires airborne isolation and microbiologic evaluation with multiple sputum specimens; NAAT on at least one accelerates confirmation, while culture remains essential for susceptibility testing. A omits molecular testing that should be performed on at least one specimen. B undersamples active pulmonary disease. C uses droplet rather than airborne precautions. E uses inadequate precautions and substitutes an infection assay for the recommended molecular test on respiratory material.

Reference: CDC Core Curriculum: laboratory testing for tuberculosis. https://www.cdc.gov/tb/webcourses/tb101/page17037.html CDC domestic tuberculosis guidance. https://www.cdc.gov/immigrant-refugee-health/hcp/domestic-guidance/tuberculosis.html