65 Clinical outcomes of chronic “Prairie Epidemic Strain” Pseudomonas aeruginosa infection in adults with cystic fibrosis

OBJECTIVES: Transmissible Pseudomonas aeruginosa (PA) strains have been described in CF and may be associated with a poorer prognosis. The “Prairie Epidemic Strain” (PES) has been recently identified in up to 30% of patients at prairie-based CF centres, however, its clinical impact remains to be determined. METHODS: A cohort study of adults with cystic fibrosis from 1981–2014 was conducted and all PA isolates from clinical visits were prospectively collected. PA strain typing at clinic enrolment, and most recent was conducted by PFGE. Patients were divided into one of four cohorts: no PA, transient PA, unique chronic PA, and chronic PES. Random effects and proportional Cox hazard models were conducted for outcome of death, transplantation and FEV1% decline. RESULTS: 204 patients (54% male) with CF were analysed: 38 no PA, 20 transient PA, 103 unique PA, 43 PES. Baseline FEV1% was lowest in the chronic PES group (p = 0.002). Overall rate of FEV1% decline was –1.19%/year (95% CI: –1.41 to –0.97, p<0.001); the chronic PES group had the greatest rate of decline at –1.24%/year (p<0.001). There were a total of 42 deaths and 37 transplants through 1862 and 2050 follow-up years, respectively. The age-adjusted hazard ratio (HR) for death was not different for the PA groups compared to the no PA group. Relative to the no PA group, risk of transplant was increased in those with chronic PES (HR 9.13, CI 1.29–69, p = 0.032) compared to the no PA group. CONCLUSION: Chronic PES infection is significantly associated with a greater rate of FEV1% decline and risk of lung transplantation but not with increased risk of death compared to no PA infection.