Mask Sampling for Mycobacterium tuberculosis: Insights into detection and transmission

Introduction:

My prior work piloted a non-invasive mask sampling tool that captured Mycobacterium tuberculosis (Mtb) directly from exhaled breath. It had the potential to provide a clearer understanding of airborne Mtb release by infected individuals, providing insights into Mtb transmission and improved diagnostics.

Objectives:

Establish a standard method of mask sampling and compare its Mtb capture with that of the Cough Aerosol Sampling System (CASS) Use mask sampling to:

o Understand the total daily output of Mtb by individuals

o Relate mask captured Mtb to infection in household contacts o Assess its potential value in aiding diagnosis

Methods:

Following optimisation of Mtb DNA detection and quantification, mask sampling was used in a series of clinical studies in sub-Saharan Africa. Repeated sampling over 24 hours examined daily output and compared this with Mtb output in sputum and other -ray changes). Mtb captured by CASS and mask was compared, as was the relationship between mask output and infection in household contacts. Finally, the potential use of mask sampling as an active case finding tool was assessed.

Results:

Different patterns of exhaled Mtb were established and mask captured output did not closely correlate with traditional markers of infectivity. Mtb was more readily detected by mask than CASS and a high mask output predicted of Mtb infection in household contacts (OR 3.20, 95%CI: 1.26-8.12, p=0.01). Mask sampling diagnosed TB earlier than sputum sampling in 4/7 microbiologically confirmed individuals during an active case finding pilot.

Conclusions:

Mask sampling can be successfully used to measure airborne Mtb output and both diagnose infection in individuals and predict infection in household contacts. Further work is needed to understand its role in routine clinical and public health practice.