Pseudomonas aeruginosa population biology in chronic obstructive pulmonary disease

Background. The role played by airway infections with Pseudomonas aeruginosa in the course and pathogenesis of chronic obstructive pulmonary disease (COPD) has not yet been resolved. We report on the molecular epidemiology and population biology of P. aeruginosa in COPD. Methods. P. aeruginosa isolates collected from adults with COPD during a 10-year prospective study were genotyped in 56 binary marker loci of core and accessory genomes. Results. The typing of 134 P. aeruginosa COPD isolates uncovered 60 unrelated bacterial clones. The worldwide dominant clones in the P aeruginosa population were also the most abundant clones among the COPD isolates. Sporadic or intermittent infection with P aeruginosa was typical for the airways of patients with COPD. Sequential isolates with the same genotype of the core genome diversified the composition of their accessory genome during the course of the infection. Conclusions. Intraclonal microevolution and the frequent turnover or loss of clones are typical for infections with P aeruginosa in COPD. This epidemiological signature differs from that of the chronic carriage of the same P aeruginosa clone in patients with cystic fibrosis.