Extensive diversification is a common feature of Pseudomonas aeruginosa populations during respiratory infections in cystic fibrosis

BACKGROUND: Populations of the Liverpool Epidemic Strain (LES) of Pseudomonas aeruginosa undergo extensive diversification in the cystic fibrosis (CF) lung during long-term chronic infections. METHODS: We analyzed sets of 40 isolates from the sputa of five CF patients, each chronically infected with a different non-LES strain of P. aeruginosa. For each sample (two per patient), diversity was assessed by characterizing nine phenotypic traits. RESULTS: All P. aeruginosa populations were highly diverse, with the majority of phenotypic variation being due to within-sample diversity. CONCLUSIONS: Maintenance of diverse populations in the CF lung is a common feature of P. aeruginosa infections.