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Original Article
Long-term clinical outcomes of ‘Prairie Epidemic Strain’ Pseudomonas aeruginosa infection in adults with cystic fibrosis
  1. Ranjani Somayaji1,
  2. John C Lam1,
  3. Michael G Surette2,
  4. Barbara Waddell3,
  5. Harvey R Rabin4,
  6. Christopher D Sibley1,
  7. Swathi Purighalla3,
  8. Michael D Parkins4
  1. 1Department of Medicine, University of Calgary, Calgary, Alberta, Canada
  2. 2Departments of Medicine, and Biochemistry and Biomedical Sciences, The Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
  3. 3Department of Microbiology, Immunology & Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
  4. 4Departments of Medicine, and Microbiology, Immunology & Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
  1. Correspondence to Dr Michael D Parkins, 3330 Hospital Drive NW, Calgary, Alberta, Canada T2N 4N1; mdparkin{at}


Rationale Epidemic Pseudomonas aeruginosa (PA) plays an important role in cystic fibrosis (CF) lung disease. A novel strain, the ‘Prairie Epidemic Strain’ (PES), has been identified in up to 30% of patients in Prairie-based Canadian CF centres.

Objective To determine the incidence, prevalence and long-term clinical impact of PES infection.

Methods A cohort of adults with CF was followed from 1980 to 2014 where bacteria isolated from clinical encounters were prospectively collected. Strain typing was performed using pulse-field gel electrophoresis and multilocus sequence typing. Patients were divided into one of four cohorts: no PA, transient PA, chronic PA with unique strains and chronic PES. Proportional Cox hazard and linear mixed models were used to assess for CF-associated respiratory death or transplantation, and rates of %FEV1 and body mass index (BMI) decline.

Results 274 patients (51.7% male) were analysed: 44––no PA, 29––transient PA, 137––unique PA, 64––PES. A total of 92 patients (33.6%) died or underwent lung transplantation (2423.0 patient-years). PES infection was associated with greater risk of respiratory death or lung transplant compared with the no PA group (aHR, 3.94 (95% CI 1.18 to 13.1); p=0.03) and unique PA group (aHR, 1.75 (95% CI 1.05 to 2.92) p=0.03). Rate of lung function decline (%FEV1 predicted) was greatest in the PES group (1.73%/year (95% CI 1.63% to 1.82%); p<0.001). BMI improved over time but at an attenuated rate in the PES group (p=0.001).

Conclusions Infection with PES was associated with increased patient morbidity through three decades and manifested in an increased risk of respiratory death and/or lung transplantation.

  • Cystic Fibrosis
  • Respiratory Infection
  • Bacterial Infection
  • Clinical Epidemiology

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