Aerosolization of viable Mycobacterium tuberculosis bacilli by tuberculosis clinic attendees independent of sputum-GeneXpert status

The potential for bioaerosol release of Mycobacterium tuberculosis ( Mtb ) during different tuberculosis (TB) disease states is poorly understood. We quantified viable aerosolized Mtb from presumptive TB patients on diagnosis and, thereafter, through six months’ standard chemotherapy. At presentation, TB clinic attendees (n=102) were classified by laboratory, radiological, and clinical features into Group A: Sputum-GeneXpert-positive TB (n=52), Group B: Sputum-GeneXpert-negative TB (n=20), or Group C: TB not diagnosed (n=30). All were assessed for Mtb bioaerosol release at baseline, and subsequently at two weeks, two months, and six months. In Groups A and B, comprising notified TB cases, Mtb was isolated from 92% and 90% of participants at initial presentation; 87% and 74% at two weeks; 54% and 44% at two months; and 32% and 20% at six months, respectively. Surprisingly, similar numbers were detected in Group C: 93%, 70%, 48%, and 22% at the same timepoints. We also observed a temporal association between Mtb bioaerosol release and TB symptoms in all three groups, with 30% of participants remaining Mtb bioaerosol positive at six months irrespective of TB chemotherapy. Captured Mtb bacilli were predominantly acid-fast stain-negative and poorly culturable; however, following in vitro incubation, one sputum-GeneXpert-positive and two sputum-GeneXpert-negative aerosol samples yielded sufficient biomass for whole-genome sequencing, revealing two different Mtb lineages. The detection of viable aerosolized Mtb in most clinic attendees at presentation, independent of TB diagnosis, suggests that unidentified Mtb transmitters could account for a significant attributable proportion of community exposure. However, longitudinal studies are required to investigate this possibility. One Sentence Summary: M. tuberculosis bacilli are detected in bioaerosols of presumptive tuberculosis (TB) patients irrespective of final TB diagnosis and clear over time. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement RW discloses support for this work from the South African Medical Research Council [MRC-RFA-UFSP-01-2013/CCAMP] and the National Institute of Allergy and Infectious Diseases of the US National Institutes of Health under award number R01AI147347 and through the Myco3V Tuberculosis Research Unit (U19AI162584). DFW acknowledges the support of the Strategic Health Innovations Partnerships (SHIP) Unit of the South African Medical Research Council with funds from National Treasury under its Economic Competitiveness and Support Package, and is grateful for funding from the Research Council of Norway (R&D Project 309592). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This study was approved by the Human Research Ethics Committee (HREC/REF: 529/2019) of the University of Cape Town. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors