Evolution of the AUST-2 prevalent strain of Pseudomonas aeruginosa in Australian CF patients

AUST-2 is one of the most common Pseudomonas aeruginosa (PA) clones in Australian cystic fibrosis (CF) patients. It is particularly common in Brisbane, Queensland (Qld.) and Perth, Western Australia (WA) on opposite sides of the continent, but is also found in other cities. We sequenced the genomes of 45 isolates from 31 patients. We have found that these isolates are highly clonal and thus probably had a single jump from environment to patient followed by spread between patients. We estimate that this initial infection event occurred in the 1990s. We also found that an aadB aminoglycoside resistance gene previously found in Brisbane AUST-2 isolates is located on a plasmid. Some of the isolates from Perth had DNA repair gene mutations and thus had taken on a mutator phenotype, acquiring numerous unique mutations. Whereas in Queensland, isolates differing by only one or two single nucleotide variations were found in different patients