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PLoS Genet. 2012 Sep;8(9):e1002928. doi: 10.1371/journal.pgen.1002928. Epub 2012 Sep 13.

Genomics of adaptation during experimental evolution of the opportunistic pathogen Pseudomonas aeruginosa.

Author information

1
Department of Biology, Carleton University, Ottawa, Canada. Alex_Wong@carleton.ca

Abstract

Adaptation is likely to be an important determinant of the success of many pathogens, for example when colonizing a new host species, when challenged by antibiotic treatment, or in governing the establishment and progress of long-term chronic infection. Yet, the genomic basis of adaptation is poorly understood in general, and for pathogens in particular. We investigated the genetics of adaptation to cystic fibrosis-like culture conditions in the presence and absence of fluoroquinolone antibiotics using the opportunistic pathogen Pseudomonas aeruginosa. Whole-genome sequencing of experimentally evolved isolates revealed parallel evolution at a handful of known antibiotic resistance genes. While the level of antibiotic resistance was largely determined by these known resistance genes, the costs of resistance were instead attributable to a number of mutations that were specific to individual experimental isolates. Notably, stereotypical quinolone resistance mutations in DNA gyrase often co-occurred with other mutations that, together, conferred high levels of resistance but no consistent cost of resistance. This result may explain why these mutations are so prevalent in clinical quinolone-resistant isolates. In addition, genes involved in cyclic-di-GMP signalling were repeatedly mutated in populations evolved in viscous culture media, suggesting a shared mechanism of adaptation to this CF-like growth environment. Experimental evolutionary approaches to understanding pathogen adaptation should provide an important complement to studies of the evolution of clinical isolates.

PMID:
23028345
PMCID:
PMC3441735
DOI:
10.1371/journal.pgen.1002928
[Indexed for MEDLINE]
Free PMC Article

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