Diagnostic accuracy of swab-based molecular tests for tuberculosis using novel near point-of-care platforms: A multi-country evaluation
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Background
Swab-based molecular platforms that enable testing of both sputum (via swabs swirled in sputum) and tongue swabs are emerging as a promising option for more accessible and lower cost molecular testing for tuberculosis (TB). We conducted a multi-country evaluation of two novel swab-based molecular tests: Molbio Truenat MTB Ultima (MTB Ultima) and Pluslife MiniDock MTB Test (MiniDock MTB).
Methods
Consecutive people ≥12 years old with presumptive TB were enrolled at outpatient health centers in India, Uganda, and Vietnam. We collected two tongue swabs and prepared two sputum swabs for MTB Ultima and MiniDock MTB testing, then evaluated the diagnostic accuracy of MTB Ultima and MiniDock MTB using both swab types against a sputum liquid culture-based microbiological reference standard (MRS). The diagnostic accuracy of swab-based molecular tests was also compared to sputum Xpert MTB/RIF Ultra (Xpert Ultra) and auramine smear microscopy.
Findings
From January to September 2024, 1,050 participants were included in the tongue swab MTB Ultima evaluation, 197 in the sputum swab MTB Ultima evaluation, and 322 in the MiniDock MTB evaluations. In comparison to sputum Xpert Ultra, sensitivity was similar for both sputum swab MTB Ultima (93.6% vs. 100.0%, difference -6.4%, [95% CI: -15.5, 2.7], p=0.25) and MiniDock MTB (91.0% vs. 94.0%, difference –3.0% [95% CI: -8.6, 2.6], p=0.50). In comparison to sputum smear microscopy, sensitivity was higher for both tongue swab MTB Ultima (77.9% vs. 59.1%, difference 18.8% [95% CI: 10.8, 26.8], p<0.0001) and MiniDock MTB (85.7% vs. 67.1%, difference 18.6% [95% CI: 7.2, 29.9], p=0.001). Specificity was high (>98%) for both tests with sputum swabs and tongue swabs.
Interpretation
MTB Ultima and MiniDock MTB have similar accuracy to current sputum-based molecular tests with sputum swabs and meet minimum accuracy thresholds for a non-sputum, near point-of-care molecular test with tongue swabs. These tests offer strong potential to make universal molecular testing for TB a reality.
