Tongue Swab TB Test is Simple, Accessible, and Accurate Test for Diagnosing TB: Study
USA: A new tuberculosis (TB) test using tongue swabs shows promising accuracy and eliminates the need for sputum samples, which many patients (25–40%) are unable to produce. This limitation in current diagnostics contributes to the underdiagnosis of Mycobacterium tuberculosis. The new test, highlighted in recent findings, could significantly expand access to molecular TB testing and improve case detection rates.
The study, published in The New England Journal of Medicine, was led by Seda Yerlikaya from Heidelberg University Hospital and collaborators across multiple countries. It evaluated the performance and usability of the MiniDock MTB test, a near–point-of-care molecular diagnostic designed for decentralized healthcare settings.
Researchers conducted a prospective, cross-sectional study across outpatient centers in countries including India, Nigeria, the Philippines, South Africa, Uganda, Vietnam, and Zambia. A total of 1,380 individuals aged 12 years or older with suspected pulmonary TB were enrolled. Among them, 18.5% were living with HIV, and 16.4% had culture-confirmed TB. The MiniDock MTB test was performed using both sputum swabs and tongue swabs, and its diagnostic accuracy was compared with standard methods such as sputum culture, smear microscopy, and the Xpert MTB/RIF Ultra assay.
The study led to the following findings:
- MiniDock MTB showed a sensitivity of 85.7% with sputum samples and 79.6% with tongue swabs.
- Specificity exceeded 97.5% for both sputum and tongue swab testing.
- The sensitivity of MiniDock MTB with sputum samples was comparable to that of the Xpert MTB/RIF Ultra assay, with only a minimal difference.
- The test demonstrated significantly higher sensitivity than conventional smear microscopy for both sputum and tongue swab samples.
- The diagnostic performance met the benchmarks set by the World Health Organization for near–point-of-care TB tests.
- These benchmarks include ≥85% sensitivity for sputum samples and ≥75% for non-sputum samples, along with specificity above 98%.
- The device showed good usability, with a median system usability score of 75.
- Healthcare workers found the test practical and easy to use in clinical settings.
- No adverse events or safety concerns related to the test were reported.
Despite these encouraging findings, the researchers acknowledged certain limitations. The study was conducted under controlled research conditions, which may not fully reflect real-world performance. Additionally, the reference standard used for comparison has inherent limitations, particularly in patients with HIV or low bacterial load, which could influence accuracy estimates. Some patient subgroups were also relatively small, potentially affecting the precision of subgroup analyses.
Overall, the MiniDock MTB test represents a promising advancement in TB diagnostics, particularly for settings where sputum collection is challenging. By enabling accurate detection using simpler, non-invasive samples, it has the potential to enhance early diagnosis and improve TB control efforts globally.
Reference:
DOI: 10.1056/NEJMoa2509761
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