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Tuberculosis contact investigation and latent tuberculosis infection — MSRA MCQ

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HardInfectious DiseasesTuberculosis contact investigation and latent tuberculosis infectionMSRA

A 36-year-old woman with Crohn's disease is reviewed in general practice before planned commencement of adalimumab. She has taken prednisolone 20 mg daily for 6 weeks. Her husband has newly diagnosed, sputum smear-positive, drug-sensitive pulmonary tuberculosis; they shared a bedroom until yesterday and he started treatment yesterday. She has no cough, fever, night sweats, weight loss or lymphadenopathy. She received BCG vaccination at school. As part of contact investigation, her Mantoux test shows 7 mm induration and her interferon-gamma release assay is positive. Liver function tests are normal and she is not pregnant. What is the most appropriate management today?

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Correct answer: E — Arrange urgent TB-service assessment to exclude active tuberculosis, then offer latent tuberculosis treatment if active disease is excluded

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

This is a close household contact of a person with infectious pulmonary TB who has evidence of TB infection: a Mantoux result of 7 mm is positive at the 5 mm threshold regardless of BCG history, and the IGRA is also positive. Her planned anti-TNF therapy and current corticosteroid exposure increase the risk that latent infection will progress to active TB. However, neither Mantoux nor IGRA distinguishes latent from active TB. NICE therefore requires assessment for active TB before latent TB infection treatment is offered. This should be coordinated urgently through the TB service, particularly given impending biologic immunosuppression. If active disease is excluded, she should be offered treatment for latent TB because she is under 65 years, is a close contact of drug-sensitive pulmonary TB and has positive tests. A is wrong because BCG does not alter the 5 mm Mantoux threshold in this setting. B omits the essential preceding exclusion of active TB. D inappropriately delays assessment and does not address the positive tests or imminent immunosuppression. E is wrong because positive testing in this high-risk close contact warrants active-disease assessment and, if excluded, preventive treatment.

Reference: NICE NG33: Tuberculosis — Recommendations (Last updated February 2024) — https://www.nice.org.uk/guidance/ng33/chapter/Recommendations NICE NG33: Tuberculosis — Recommendations (Last updated February 2024) — https://www.nice.org.uk/guidance/ng33/chapter/Recommendations NICE NG33: Tuberculosis — Recommendations (Last updated February 2024) — https://www.nice.org.uk/guidance/ng33/chapter/Recommendations