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Saliva collection

Saliva Beats Swabs for Rapid Tuberculosis Detection

Publication Title: Diagnostic Accuracy of Molecular Testing on Saliva and Oral Swabs for Pulmonary Tuberculosis

Summary

Question

This study examined the diagnostic accuracy of molecular testing on saliva and oral swabs for detecting pulmonary tuberculosis (TB), using sputum culture as the reference standard. The researchers aimed to determine whether these minimally invasive methods could serve as reliable alternatives for TB diagnosis.

Why it Matters
Tuberculosis remains a global health challenge, with millions of cases undetected each year. Sputum, the standard sample for diagnosing pulmonary TB, is difficult to collect from certain groups, such as children and people with HIV. Additionally, sputum collection poses risks of airborne infection. Non-sputum methods, like saliva and oral swabs, offer a safer and simpler alternative that could expand access to diagnostic testing, particularly in community settings or for individuals unable to provide sputum. This research contributes to efforts to meet the World Health Organization’s diagnostic targets for TB and improve case detection worldwide.
Methods
The researchers conducted a nested case–control study within a prospective cohort of individuals undergoing TB evaluation at primary care centers in Cali, Colombia, between July 2023 and August 2024. Saliva and oral swabs were collected from participants alongside sputum samples. Molecular testing using the Xpert MTB/RIF Ultra assay was performed on thawed saliva and swab samples, with results compared to sputum culture data. Sensitivity and specificity of the saliva and swab tests were calculated.
Key Findings
Saliva testing achieved a sensitivity of 90.5% and specificity of 95.8%, while swabs had a sensitivity of 71.6% and specificity of 98.9%. Saliva outperformed swabs in sensitivity by 18.9%, meeting the World Health Organization’s target of ≥80% sensitivity for nonsputum TB diagnostics. Both methods were highly specific, exceeding the target of ≥98%. Over 95% of participants found the sample collection procedures acceptable.
Implications
Saliva testing presents a promising alternative for diagnosing pulmonary TB in patients who cannot produce sputum, offering high sensitivity and specificity. Oral swabs provide another option but with lower sensitivity. These methods could reduce reliance on invasive procedures and improve TB detection in community-based settings, particularly for children, people with HIV, and asymptomatic individuals.
Next Steps
Future research should focus on optimizing sample processing to improve sensitivity, exploring the feasibility of saliva and swab testing in community and home-based settings, and evaluating their accuracy in populations with lower bacterial loads, such as children and asymptomatic individuals.
Funding Information
This research was supported by the National Institute of Allergy and Infectious Diseases (grant R21AI174129) and the Fogarty International Center of the National Institutes of Health (grant D43TW006589). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Full Citation

Vargas D, Fuertes-Bucheli J, Sanchez-Hidalgo A, Palomares Velosa J, Lasso A, Gupta A, Martinez-Valencia A, Díaz G, Luna L, Alexander N, Ferro B, Davis J. Diagnostic Accuracy of Molecular Testing on Saliva and Oral Swabs for Pulmonary Tuberculosis. Clinical Infectious Diseases 2026, ciag055. PMID: 41817395, DOI: 10.1093/cid/ciag055.
This AI-assisted summary has been reviewed and approved by at least one of the study's authors to ensure it accurately reflects the research.

Authors

  • Deninson Alejandro Vargas

    First Author
    School Building Streamline Icon: https://streamlinehq.comOther Institution

  • Luke Davis, MD

    Last Author
    Yale School of Medicine

    Associate Professor of Epidemiology (Microbial Diseases) and of Medicine (Pulmonary, Critical Care and Sleep Medicine); Affiliated Faculty, Yale Institute for Global Health

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Other Authors

  • Jose Fernando Fuertes-Bucheli;
  • Andrea Sanchez-Hidalgo;
  • Jairo Palomares Velosa;
  • Alvaro Mauricio Lasso;
  • Amanda J Gupta;
  • Alvaro J Martinez-Valencia;
  • Gustavo Díaz;
  • Lucy Luna;
  • Neal Alexander;
  • Beatriz Eugenia Ferro

Research Themes

Concepts