Exhaled breath aerosol sampling for detection of pulmonary tuberculosis in adults: a study protocol for an exploratory diagnostic accuracy study

Introduction Tuberculosis remains a major global health challenge, causing over one million deaths annually. Current diagnostic techniques depend on restrictive sputum sampling. Better sampling methods are needed to enable early detection and effective management. This study introduces exhaled breath aerosol sampling as a new, non-invasive method for diagnosing respiratory infections. Methods and analysis This prospective cross-sectional monocentric study uses an innovative face mask-based breath sampling device. Up to 300 participants aged 18 years and older with symptoms suggestive of TB disease will be recruited from outpatient clinics in Bucharest and screened for eligibility. Participants will be invited to give one exhaled breath sample using the face mask sampling device, one tongue swab sample and one sputum sample. Routine standard of care services will be conducted per local practices. Collected exhaled breath samples will be tested using quantitative real-time polymerase chain reaction for Tuberculosis and Rifampicin resistance detection. The diagnostic accuracy of the exhaled breath sampling with subsequent molecular testing will be assessed in comparison to results of tongue swab and sputum sampling coupled with microbiological culture. In addition to the diagnostic accuracy assessment, the study will explore acceptability and usability of the exhaled breath sampling devices through observation, in-depth interviews and focus group discussions involving both participants and healthcare workers. Ethics and dissemination Ethical approval has been granted by all relevant institutional review boards prior to study initiation, and informed consent will be obtained from all participants. The study was registered on the German Clinical Trials Register (DRKS) on April 16 th 2025 prior to the first participant enrollment. Strengths • Novel method for exhaled breath aerosol collection and detection of infectious pathogens • Prospective cross-sectional study will be conducted in high TB burden setting • Mixed-methods approach used to investigate feasibility, acceptability, and usability of sampling Limitations • Limited generalizability