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TB Reactivation on Biologics — RACP Adult Medicine MCQ

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ModerateInfectious DiseasesTB Reactivation on BiologicsRACP Adult Medicine

A 40-year-old man with ankylosing spondylitis on adalimumab presents with 2 weeks of cough, fever, and night sweats. CXR shows right upper lobe consolidation with a cavitary lesion. Sputum AFB smear is positive. Mantoux was not done prior to biologic initiation. What is the most likely diagnosis?

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Correct answer: A — Reactivation tuberculosis

Cavitary upper lobe consolidation with positive AFB smear in a patient on anti-TNF therapy (adalimumab) is reactivation TB until proven otherwise. Anti-TNF agents increase TB reactivation risk 5–30×. Pre-biologic TB screening (Mantoux or IGRA plus CXR) is mandatory. This was missed. Treatment is standard 4-drug anti-TB therapy (2RHZE/4RH). Adalimumab must be ceased.

Reference: eTG Antibiotic – 2025 – TB; TSANZ 2024; eTG Rheumatology 2024