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ERJ Open Res. 2018 Jun 18;4(2). pii: 00162-2017. doi: 10.1183/23120541.00162-2017. eCollection 2018 Apr.

Epidemiology and natural history of Pseudomonas aeruginosa airway infections in non-cystic fibrosis bronchiectasis.

Author information

Dept of Biological Sciences, University of Calgary, Calgary, Canada.
Dept of Medicine, University of Calgary, Calgary, Canada.
Dept of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Canada.
Dept of Medicine and Dept of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada.


The natural history and epidemiology of Pseudomonas aeruginosa infections in non-cystic fibrosis (non-CF) bronchiectasis is not well understood. As such it was our intention to determine the evolution of airway infection and the transmission potential of P. aeruginosa in patients with non-CF bronchiectasis. A longitudinal cohort study was conducted from 1986-2011 using a biobank of prospectively collected isolates from patients with non-CF bronchiectasis. Patients included were ≥18 years old and had ≥2 positive P. aeruginosa cultures over a minimum 6-month period. All isolates obtained at first and most recent clinical encounters, as well as during exacerbations, that were morphologically distinct on MacConkey agar were genotyped by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). A total of 203 isolates from 39 patients were analysed. These were compared to a large collection of globally epidemic and local CF strains, as well as non-CF isolates. We identified four patterns of infection in non-CF bronchiectasis including: 1) persistence of a single strain (n=26; 67%); 2) strain displacement (n=8; 20%); 3) temporary disruption (n=3; 8%); and 4) chaotic airway infection (n=2; 5%). Patterns of infection were not significant predictors of rates of lung function decline or progression to end-stage disease and acquisition of new strains did not associate with the occurrence of exacerbations. Rarely, non-CF bronchiectasis strains with similar pulsotypes were observed in CF and non-CF controls, but no CF epidemic strains were observed. While rare shared strains were observed in non-CF bronchiectasis, whole-genome sequencing refuted patient-patient transmission. We observed a higher incidence of strain-displacement in our patient cohort compared to those observed in CF studies, although this did not impact on outcomes.

Conflict of interest statement

Conflict of interest: R. Somayaji has received research fellowship funding from Cystic Fibrosis Canada, Alberta Innovates and the Canadian Institutes of Health Research, and grants from Cystic Fibrosis Canada, the Canadian Institute of Health Research and the Royal College of Physicians and Surgeons outside the submitted work. M.D. Parkins has received research funding from Cystic Fibrosis Canada, the Canadian Institute of Health Research, the Lung Association of Alberta and the Northwest Territories, Gilead Sciences, The University of Calgary and Calgary Laboratory Services.

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