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Isoniazid-Resistant TB — SCE Infectious Diseases MCQ

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HardTuberculosisIsoniazid-Resistant TBSCE Infectious Diseases

A patient receiving directly observed treatment for pulmonary tuberculosis remains culture-positive at month 2. Baseline disease was reported rifampicin-sensitive. What is the most important next step before empirically redesigning or extending the regimen?

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Correct answer: A — Repeat culture and susceptibility testing

Persistent culture positivity requires a tuberculosis specialist assessment of adherence, dose, absorption, interactions and disease burden, plus repeat culture and susceptibility testing to detect acquired or initially missed resistance. A regimen should not be improvised from a single early result. Adding one active drug risks amplifying resistance, while premature use of an MDR regimen is inappropriate without defining resistance.

Reference: https://www.nice.org.uk/guidance/conditions-and-diseases/infections