BACKGROUNDTongue swabs are a promising specimen type for TB diagnosis. In a previous study, using a consensus protocol, tongue swabs tested with Xpert MTB/RIF Ultra outperformed sputum smear microscopy, but a substantial proportion (6.1%) of results were non-actionable (e.g., invalid/error). We evaluated a revised protocol for tongue swab Xpert Ultra testing in four high-burden countries.METHODSParticipants aged ≥12 years with presumptive TB were enrolled from outpatient clinics in the Philippines, South Africa, Nigeria, and Zambia. Tongue swabs were processed using Sample Reagent (SR, Cepheid, USA) diluted 2:1 with phosphate buffer or phosphate-buffered saline and tested with Xpert Ultra. Diagnostic performance was assessed against culture-based microbiological reference standard and compared to sputum tests.RESULTSFrom March to November 2024, 1,168 participants were enrolled (median age 37 IQR: 28-48 years; 46.7% female; 21.8% living with HIV; 18.5% culture-confirmed TB). The proportion of non-actionable tongue swab results was 5.6% overall, but CONCLUSIONThe revised protocol yielded low error rates at most sites and moderate sensitivity, supporting tongue swabs as an alternative specimen for Xpert Ultra testing when sputum is unavailable..
Ajide et al. (Mon,) studied this question.