AveloMask, a novel breath aerosol collection kit for airborne Mycobacterium tuberculosis: a proof-of-principle assessment

BackgroundTuberculosis (TB) remains the worlds deadliest infectious disease, with sputum-based diagnostics failing to detect many active cases, often due to difficulty in specimen collection. Breath aerosols, a major route of Mycobacterium tuberculosis (MTB) transmission, offer a promising non-invasive alternative. This study evaluated the diagnostic accuracy and feasibility of the AveloMask, a novel breath aerosol collection kit, designed for point-of-care collection, for detecting active pulmonary TB using PCR. MethodsWe conducted a diagnostic accuracy study among adult outpatients with TB symptoms attending primary healthcare facilities in Cape Town, South Africa. Participants wore the mask for 45 minutes, coughing deeply five times at the start and end of collection. Breath aerosol samples were collected on a fiber filter integrated into the mask, immediately stabilized in buffer post-collection, biobanked, and later analysed by quantitative PCR (qPCR) targeting the MTB-specific IS6110 insertion sequence. Diagnostic accuracy was assessed against sputum Xpert MTB/RIF Ultra (SXRS) and a composite microbiological reference standard (MRS), including culture. Usability was evaluated using structured questionnaires. ResultsOf 61 participants enrolled, 58 provided evaluable breath samples and 59% (34/58) had confirmed TB. Compared with the SXRS, mask qPCR achieved a sensitivity of 71.0% (95% CI: 53.4-83.9%) and specificity of 92.3% (95% CI: 75.9-97.9%). Compared with the MRS, sensitivity was 64.7% (95% CI: 47.9-78.5%) and specificity 91.7% (95% CI: 74.2-97.7%). Mask qPCR positivity rates increased with higher sputum bacterial loads, reaching 100% sensitivity among participants with high sputum MTB concentrations. MTB IS6110 copy numbers in extracted mask samples varied widely (range: 4-2147 copies; mean: 175 copies), but were low overall, likely reflecting incomplete DNA recovery during lysis or extraction and/or a low number of MTB bacilli in breath aerosols. Usability feedback showed that the mask and collection procedure were well-tolerated. ConclusionsThe AveloMask breath aerosol sampling kit demonstrated promising diagnostic accuracy for active TB, comparable to other mask-based methods, while offering ease-of-use and feasibility at the point-of-care. Future studies should improve lysis and extraction and explore integration with commercial molecular diagnostic platforms, validate these findings in larger, more diverse populations, and for different use-cases.