Abstracts (first author)
Evolutionary genomics of epidemic and non-epidemic strains of Pseudomonas aeruginosa
Pseudomonas aeruginosa is an opportunistic pathogen of humans and is the most common bacterial species isolated from the respiratory tracts of adult patients with cystic fibrosis (CF). Chronic infection of the CF lung can lead to decades of direct interaction between the host and resident P. aeruginosa population. Longitudinal studies have documented the patterns of adaptation to the CF lung, and evidence to date suggests that a large number of genes are targets for mutation, but most are mutated in only a small fraction of infections. A more comprehensive view therefore requires the comparison of a larger sample of diverse clinical isolates. To this end, we obtained whole genome sequence data from a collection of P. aeruginosa isolated from the airways of CF patients in order to investigate general patterns of adaptation associated with chronic infection. We also focus attention on a transmissible, epidemic strain that was recently reported within North America. We present multiple lines of evidence that the history of selection imposed by the CF lung environment has a major influence on genomic evolution and the genetic characteristics of isolates causing contemporary infection. We identify candidate genes and important functional pathways, and find that the presence of oxidative stressors and antibiotics appear to be key factors that have driven the adaptive evolution of this pathogen within the host.