Tongue swab Xpert MTB/RIF Ultra testing for TB using a revised consensus protocol

Authors

• B. Ajide, Bingham University
• C. A. Moe, UCI School of Medicine
• J. Barrameda, De La Salle Medical and Health Sciences Institute
• M. Chirwa, Centre for Infectious Disease Research in Zambia
• L. Rockman, Stellenbosch University, Faculty of Medicine and Health Sciences
• P. de Haas, KNCV Tuberculosis Foundation
• M. de Vos, Universitätsklinikum Heidelberg
• M. Kato-Maeda, University of California, San Francisco
• B. Tasca, KNCV Tuberculosis Foundation
• J. Bimba, Bingham University
• C. Yu, De La Salle Medical and Health Sciences Institute
• C. M. Denkinger, Universitätsklinikum Heidelberg
• K. Kremer, KNCV Tuberculosis Foundation
• P. Nahid, University of California, San Francisco
• A. Cattamanchi, UCI School of Medicine
• G. Theron, Stellenbosch University, Faculty of Medicine and Health Sciences
• M. Muyoyeta, Centre for Infectious Disease Research in Zambia

Publication Date

4-27-2026

Document Type

Article

Publication Title

International Journal of Tuberculosis and Lung Disease the Official Journal of the International Union Against Tuberculosis and Lung Disease

Abstract

BACKGROUND: Tongue 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.

METHODS: Participants 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.

RESULTS: From 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 < 4% in all countries except South Africa (15.4%). Tongue swab sensitivity was 66.0% (95% CI: 59.0-72.5); specificity was 99.6% (95% CI: 98.9-99.9).

CONCLUSION: The 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..

First Page

211

Last Page

216

APA Citation

Ajide, B., Moe, C., Barrameda, J., Chirwa, M., Rockman, L., de Haas, P., de Vos, M., Kato-Maeda, M., Tasca, B., Bimba, J., Yu, C., Denkinger, C., Kremer, K., Nahid, P., Cattamanchi, A., Theron, G., & Muyoyeta, M. (2026). Tongue swab Xpert MTB/RIF Ultra testing for TB using a revised consensus protocol. International Journal of Tuberculosis and Lung Disease the Official Journal of the International Union Against Tuberculosis and Lung Disease, 30(5); 211-216. https://doi.org/10.5588/ijtld.25.0520