High aerosol production of potentially infectious cough aerosols in people with cystic fibrosis during coughing

Abstract

Objectives: Our group has investigated the extent of Pseudomonas aeruginosa aerosol release during cough in people with CF (Knibbs, Thorax, 2014; Wood, AJRCCM, 2018; Stockwell, AJRCCM, 2018). We have demonstrated the concentration of P. aeruginosa cough aerosols is highly variable between patients, yet the only factor associated with aerosol concentration is the sputum concentration of the pathogen. Therefore, we aimed to investigate (using the merged datasets) if additional clinical factors are associated with aerosol production. Methods: The merged P. aeruginosa cough aerosol study datasets were analysed for factors associated with cough aerosol production. Participants were categorised into high producers if the P. aeruginosa aerosol count was ≥10 colony forming units (CFU) or low producers if the count was <10 CFU (Jones-Lopez, AJRCCM, 2013). Results: Fifty-two people with CF and chronic P. aeruginosa infection performed 68 cough tests. P. aeruginosa sputum concentration was the only factor associated with P. aeruginosa aerosol concentration (r = 0.61;p < 0.001). No associations were seen for gender (p = 0.78), FEV1% predicted (r = −0.025;p = 0.86), BMI (r = −0.23;p = 0.11), age (r = 0.22;p = 0.13), modulator use (p = 0.47), C-reactive protein level (r = −0.24;p = 0.87) or other pathogens in sputum (p = 0.16). The sputum concentration association was also seen in 12 subjects who were recruited to multiple (2–3) cough tests. Over time, the cough aerosol category did not change in 9 subjects (8/9 remained high producer; 1/9 remained low producer) but did change in 3 subjects (2/3 changed from high to lowproducers; 1/3 changed from low to high producer). Conclusions: P. aeruginosa sputum concentration strongly predicts for P. aeruginosa cough aerosol concentration. Production of cough aerosol (high or low producers) was unchanged over time for most participants. Grant Support: Cystic Fibrosis Foundation Therapeutics (USA), The Prince Charles Hospital Foundation, Advance Queensland.L20019766842019-11-07 <br />