Epidemiology of Clonal Pseudomonas aeruginosa Infection in a Canadian Cystic Fibrosis Population

Rationale: The extent of the genetic relatedness among Pseudomonas aeruginosa isolates and its impact on clinical outcomes in the cystic fibrosis (CF) population is poorly understood.Objectives: The objectives of this study were to determine the prevalence of clonal P. aeruginosa infection in Canada and to associate P. aeruginosa genotypes with clinical outcomes.Methods: This was an observational study of adult and pediatric patients with CF across Canada. Isolates were typed using multilocus sequence typing. A clone was defined as sharing at least six of seven alleles. Genotyping results were associated with clinical outcomes, including forced expiratory volume in 1 second, body mass index, rate of pulmonary exacerbation, and death/transplant.Results: A total of 1,537 P. aeruginosa isolates were genotyped to 403 unique sequence types (STs) in 402 individuals with CF. Although 39% of STs were shared, most were shared only among a small number of subjects, and the majority (79%) of the genetic diversity in...