Pseudomonas aeruginosaadaptation and diversification in the non-cystic fibrosis bronchiectasis lung

Abstract

To characterisePseudomonas aeruginosapopulations during chronic lung infections of non-cystic fibrosis bronchiectasis patients, we used whole-genome sequencing to 1) assess the diversity of P. aeruginosaand the prevalence of multilineage infections; 2) seek evidence for cross-infection or common source acquisition; and 3) characteriseP. aeruginosaadaptations.189 isolates, obtained from the sputa of 91 patients attending 16 adult bronchiectasis centres in the UK, were whole-genome sequenced.Bronchiectasis isolates were representative of the widerP. aeruginosapopulation. Of 24 patients from whom multiple isolates were examined, there were seven examples of multilineage infections, probably arising from multiple infection events. The number of nucleotide variants between genomes of isolates from different patients was in some cases similar to the variations observed between isolates from individual patients, implying the possible occurrence of cross-infection or common source acquisition.Our data indicate that during infections of bronchiectasis patients,P. aeruginosapopulations adapt by accumulating loss-of-function mutations, leading to changes in phenotypes including different modes of iron acquisition and variations in biofilm-associated polysaccharides. The within-population diversification suggests that larger scale longitudinal surveillance studies will be required to capture cross-infection or common source acquisition events at an early stage.