Aerosol production associated with different respiratory manoeuvres and face coverings, and two weeks of treatment in people with tuberculosis

Title : Aerosol production associated with different respiratory manoeuvres and face coverings, and two weeks of treatment in people with tuberculosis

Abstract:

Background: Mycobacterium tuberculosis transmits person-to-person via aerosols. The effect of different respiratory manoeuvres and accessible yet non-conventional face coverings (paper mask, neck gaiter, bandana, and surgical masks) require clarification, as well as how these readouts compare before and after two weeks treatment.

Methods: A Human Aerosol Chamber captured aerosols after tidal breathing, spontaneous cough, and forced cough. Each participant with tuberculosis (n=34) did three respiratory manoeuvres, twice on consecutive days (one with a specific face covering and the other without). Particles were quantified in size categories, aged (airborne) aerosols were captured using a six-stage Andersen Cascade Impactor (solid culture) and BioSamplers (liquid culture, Xpert MTB/RIF Ultra). This was repeated after two weeks of effective treatment without face coverings.

Results: Cough had the highest proportion of people with at least one positive bacteriological result with 30% (8/27), 47% (16/34), and 62% (21/34), from tidal breathing, spontaneous cough and forced cough respectively without face covering. Tidal breathing produced more particles than spontaneous cough (but lower than forced cough). Across all pre-treatment manoeuvres, face covering reduced particles [722×10⁶ (0.018-4156×10⁶) vs. 728×10⁶ (0.005-2143×10⁶)] and Mtb CFU [median 5 (IQR 1-49) vs. 1 (0-14); p=0.039]. Mycobacterial growth supplement EPCFE significantly improved Mtb culturability from both sputum and aerosol samples, p<0.001 and p=0.023. Treatment reduced detectable Mtb DNA from 53% to 44%, culturability was reduced by 53% (17 to 8), p=0.001, only one participant remained culture positive. Treatment did not significantly change particle counts in each respiratory manoeuvre.

Conclusion: Cough remains a dominant means to aerosolise TB, but tidal breathing also carries potentially infectious aerosols. Cough frequency was not associated with TB infectiousness. Spontaneous cough had significantly higher particles at two weeks treatment when particles were stratified by size, while tidal breathing and forced cough showed no differences.

Biography:

Zama is a South African postdoctoral research fellow currently contributing to the African Microbiome Project by looking at aerosol microbiome. She has over seven years of experience working with infectious diseases, particularly tuberculosis (TB), with expanding expertise in environmental microbiology. Her approach focuses on the survival of airborne respiratory pathogens from different environments using culture-dependent and independent approaches to understand microbiome aerobiology. She continues to bridge clinical science, environmental health, and microbial ecology, with a vision rooted in One Health and social equity frameworks.