Cystic fibrosis pathogens survive for extended periods within cough-generated droplet nuclei

Abstract

The airborne route is a potential pathway in the person-to-person transmission of bacterial strains among cystic fibrosis (CF) populations. In this cross-sectional study, we investigate the physical properties and survival of common non- CF pathogens generated during coughing. We conclude that Gram-negative bacteria and are aerosolised during coughing, can travel up to 4 m and remain viable within droplet nuclei for up to 45 min. These results suggest that airborne person-to-person transmission is plausible for the CF pathogens we measured.

Transmission of bacteria in bronchiectasis and chronic obstructive pulmonary disease: Low burden of cough aerosols

“…Third, the distance that viable P. aeruginosa cough aerosols could travel in patients with bronchiectasis, COPD or CF was similar (4 m); however, the duration that P. aeruginosa cough aerosols could remain suspended in the air was shorter in patients with bronchiectasis at 15 min compared to 45 min for patients with CF . Finally, the mean concentration of P. aeruginosa in sputum in the bronchiectasis and COPD cohort did not correlate with the total aerosol count observed at 2 m, and this was in contrast to our findings in the CF cough aerosol studies …”

“…Participants performed up to five cough tests: two tests in the distance rig with aerosol collection points at 2 and 4 m (order randomized) and three tests in the duration rig with aerosol ageing periods of 5, 15 and 45 min. The distance and duration testing methodologies have been described in detail previously, with participants monitored by a healthcare professional . In brief, participants performed respiratory function testing on the day of testing to measure forced expiratory volume in 1 s (FEV 1 ) and forced vital capacity (FVC) according to the American Thoracic Society (ATS) guidelines .…”

“…Qualitative and quantitative sputum cultures were performed . The aerosol agar plates were incubated aerobically at 37°C for 72 h. Presumptive identification of P. aeruginosa isolates was based on positive oxidase reaction and growth at 42°C.…”

“…In patients with cystic fibrosis (CF) over 12 years of age, P. aeruginosa is the dominant bacterial pathogen, and cross‐infection between patients with CF attending specialist centres has been well documented . The transmission route of P. aeruginosa cross‐infection has been suggested to occur through aerosol transmission, with evidence that viable P. aeruginosa (and other CF pathogens) cough aerosols could travel for 4 m from the source (person with CF) and remain in the air for 45 min after cough . Yet, shared strains of P. aeruginosa have not been found in environmental sampling, further supporting aerosol transmission as a possible mode of cross‐infection.…”

Work environment risks for health care workers with cystic fibrosis

“…Good hand hygiene practices reduced hand contamination in patients, following CF clinic visits Cough aerosol contamination with P. aeruginosa and other common CF pathogens in droplet nuclei in the respirable size range (<5 μm) . During coughing, droplet nuclei can travel long distances (up to 4 m) and remain airborne for prolonged durations (up to 45 min) …”