Molecular TB tests are less sensitive in people living with HIV and in smear-negative disease, because the bacillary load in sputum is often low. A negative result in a symptomatic patient with HIV lowers the probability of TB but does not exclude it.
Where clinical suspicion stays high, send a further sample, request culture, and consider other specimens and tests such as urine LAM in advanced HIV. Empirical treatment remains a clinical decision when the patient is unwell.
- Keep TB on the list after a negative molecular test in a symptomatic person with HIV.
- Send a repeat sputum and request culture when suspicion stays high.
- Consider urine LAM in people with advanced HIV.
- Make a clinical decision on empirical treatment if the patient is seriously unwell.
Why it matters
Every molecular TB test loses sensitivity in exactly the patients most likely to die of missed TB.
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