RT Journal Article SR Electronic T1 Aerosolization of Mycobacterium tuberculosis by tidal breathing JF bioRxiv FD Cold Spring Harbor Laboratory SP 2021.10.17.464541 DO 10.1101/2021.10.17.464541 A1 Dinkele, Ryan A1 Gessner, Sophia A1 McKerry, Andrea A1 Leonard, Bryan A1 Leukes, Juane A1 Seldon, Ronnett A1 Warner, Digby F. A1 Wood, Robin YR 2021 UL http://biorxiv.org/content/early/2021/10/18/2021.10.17.464541.abstract AB Rationale Interrupting tuberculosis (TB) transmission requires an improved understanding of how – and when – the causative organism, Mycobacterium tuberculosis (Mtb), is aerosolized. Although Cough is commonly assumed to be the dominant source of Mtb aerosols, recent evidence of Cough-independent Mtb release implies the contribution of alternative mechanisms.Objective To compare the aerosolization of Mtb and particulate matter from GeneXpert-positive patients during three separate respiratory manoeuvres: Tidal Breathing (TiBr), Forced Vital Capacity (FVC), and Cough.Methodology Bioaerosol sampling and Mtb detection were combined with real-time assessments of CO2 production and particle counts from 39 confirmed TB patients.Measurements and Main Results TiBr and FVC produced comparable numbers of particles, with Cough producing >4-fold more. For all manoeuvres, the proportions of particles detected across size categories from 0.5 – 5 μm were similar, with minor differences observed only in particles between 1.5 – 2 μm (p = 0.014) and >5 μm (p = 0.020). Viable Mtb bacilli were detected in 66%, 70%, and 65% of TiBr, FVC, and Cough samples, respectively. Notably, while Cough produced 3-fold more Mtb than TiBr, the relative infrequency of coughing compared to breathing implies that TiBr likely contributes >90% of the daily aerosolised Mtb across a range of Cough frequencies.Conclusions Our results suggest that, while Cough increases particle aerosolization compared to TiBr, this is not associated with increased Mtb aerosolization. Instead, TiBr produces more Mtb per particle than Cough. Assuming the number of viable Mtb organisms detected provides a proxy measure of patient infectiousness, these observations imply a significant contribution of TiBr to TB transmission.Competing Interest StatementThe authors have declared no competing interest.