Swab-based TB tests show strong accuracy near the point of care

Researchers led by corresponding author Amy Steadman evaluated new swab-based molecular tests for tuberculosis (TB), a promising approach described as more accessible and lower cost compared with traditional methods. The study tested two novel platforms: Molbio Truenat MTB Ultima (MTB Ultima) and Pluslife MiniDock MTB Test (MiniDock MTB). The team enrolled consecutive people aged 12 and older with presumptive TB at outpatient health centers in India, Uganda, and Vietnam. For each participant they collected two tongue swabs and prepared two sputum swabs, and then ran MTB Ultima and MiniDock MTB on those swabs. The results from the swab-based molecular tests were evaluated against a sputum liquid culture-based microbiological reference standard (MRS), the study’s laboratory benchmark. The goal was to see whether swab-based sampling, including non-sputum tongue swabs, could deliver diagnostic accuracy comparable to established sputum-based molecular tests while operating closer to the point of care.

Between January and September 2024 the study included distinct evaluation groups: 1,050 participants for the tongue swab MTB Ultima evaluation, 197 for the sputum swab MTB Ultima evaluation, and 322 for the MiniDock MTB evaluations. Diagnostic accuracy was compared to sputum Xpert MTB/RIF Ultra (Xpert Ultra) and to auramine smear microscopy, as well as to the MRS. When compared to sputum Xpert Ultra, sensitivity was similar for sputum swab MTB Ultima (93.6% vs. 100.0%, difference -6.4%, 95% CI: -15.5, 2.7, p=0.25) and for MiniDock MTB (91.0% vs. 94.0%, difference -3.0%, 95% CI: -8.6, 2.6, p=0.50). Against sputum smear microscopy, sensitivity was higher for tongue swab MTB Ultima (77.9% vs. 59.1%, difference 18.8%, 95% CI: 10.8, 26.8, p<0.0001) and for MiniDock MTB (85.7% vs. 67.1%, difference 18.6%, 95% CI: 7.2, 29.9, p=0.001). Specificity exceeded 98% for both tests using sputum swabs and tongue swabs.

The authors conclude that Molbio Truenat MTB Ultima and Pluslife MiniDock MTB Test show similar accuracy to current sputum-based molecular tests when run on sputum swabs, and meet minimum accuracy thresholds for a non-sputum, near point-of-care molecular test when used with tongue swabs. Because the platforms performed well against both Xpert Ultra and auramine smear microscopy benchmarks and showed high specificity, the findings support the idea that swab-based molecular testing can be a reliable diagnostic option. By validating tongue swabs as a feasible non-sputum sample type under real-world outpatient conditions across India, Uganda, and Vietnam, the study points to a practical route for expanding access to molecular TB testing. The authors highlight that these tests offer strong potential to make universal molecular testing for TB a reality, suggesting a path toward broader, lower-cost deployment nearer to patients.