Face mask sampling for the detection of microbes in expelled aerosols and the impact of airway clearance on microbial yield in children with cystic fibrosis: a feasibility trial.

Background. Early identification of pulmonary exacerbations is vital for the management of cystic fibrosis (CF). Non-invasive airway sampling in preschool children can be inaccurate. Face mask sampling (FMS) is a novel non-invasive approach that can be used to assess microbial airway pathogens in patients with CF.Methods. Prospective cross-sectional study in children with CF. Children wore a suitably sized face mask fitted with two strips of a polyvinyl alcohol sampling matrix for a period of 15 min. Routine microbiology sampling using cough swab, sputum and/or bronchoalveolar lavage was completed following FMS. Children then completed their routine airway clearance with their physiotherapist. Following this, a separate face mask was worn for a further 15 min, after which further routine microbiology sampling (cough swab or sputum) was completed. The face masks were stored at room temperature before transfer and processing in the laboratory to quantify bacterial burden and identify key pathogens such as Mycobacterium abscessus and Pseudomonas aeruginosa.Results. Eleven children (six male, median age 12 years, range 1-16 years), from the Leicester CF cohort were included. All patients tolerated the FMS. Nine face mask samples from 11 participants isolated respiratory pathogens, including M. abscessus (n=3). P. aeruginosa was not detected on face mask samples. There was a trend towards an increase in microbial yield (prGen16s) following airway clearance (n=5), but this did not reach statistical significance.Conclusions. FMS systems are feasible for children and young people with CF. They may provide an effective method to detect exhaled lower airway pathogens including non-tuberculous mycobacteria. The effect of physiotherapy on the exhaled microbiome needs to be explored further.