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Latent tuberculosis — ABIM Board MCQ

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ModerateInfectious DiseaseLatent tuberculosisABIM Board

A 46-year-old who received BCG in childhood is about to start adalimumab. She has no TB symptoms but requires testing for latent infection. Which initial test is preferred?

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Correct answer: A — Use an interferon-gamma release assay

The best answer is “Use an interferon-gamma release assay”. IGRA is preferred after BCG because its antigens do not cross-react with the vaccine, whereas BCG can contribute to a false-positive tuberculin skin test. Anti-TNF therapy increases reactivation risk, so screening cannot be omitted. Sputum testing and bronchoscopy evaluate suspected active pulmonary disease, and cryptococcal antigen addresses another infection.

Reference: CDC Interferon-gamma Release Assay Guidance: https://www.cdc.gov/tb/hcp/testing-diagnosis/interferon-gamma-release-assay.html