Rapid quantitative PCR on tongue swabs for pulmonary tuberculosis in adults: a prospective multicentre study.

Summary

In a 7-center prospective study of 729 adults, tongue-swab TB-EASY qPCR achieved sensitivity/specificity of 89.6%/96.2% versus sputum Xpert and 87.4%/98.0% versus a microbiological reference, with sensitivity ranging from 100% (high load) to 70.4% (very low load). Findings support a reliable noninvasive alternative when sputum is unavailable or difficult to obtain.

Key Findings

• Sensitivity/specificity 89.6%/96.2% vs sputum Xpert; 87.4%/98.0% vs microbiological reference standard.
• Sensitivity varied with bacterial load: 100% (high), 70.4% (very low).
• Prospective multicentre design across seven TB hospitals with 729 participants.
• Identified limitations include selection of symptomatic patients, use of Xpert (not Ultra), and lack of evaluation in non-sputum producers.

Clinical Implications

Tongue-swab qPCR can expand TB testing to patients unable to produce sputum and enable decentralized screening; programs should consider adoption with attention to bacterial load effects and cost-effectiveness.

Limitations

• Potential spectrum/selection bias toward symptomatic patients; community screening not yet evaluated.
• Used sputum Xpert rather than Xpert Ultra; non-sputum-producing patients and cost-effectiveness not assessed.

Future Directions

Community-based validation, head-to-head comparison with Xpert Ultra, implementation studies on sample workflow, and cost-effectiveness in high-burden settings.