Genome-wide recombination drives diversification of epidemic strains of Acinetobacter baumannii

Wednesday, October 26, 2011 — Poster Session IV
2:00 p.m. – 4:00 p.m.	Natcher Conference Center	NHGRI	INFECTDIS-13

* FARE Award Winner

Authors

• E Snitkin
• A Zelazny
• C Montero
• F Stock
• L Mijares
• NISC Comparative Sequence Program
• P Murray
• J Segre

Abstract

Acinetobacter baumannii is an emerging human pathogen and a significant cause of nosocomial infections amongst hospital patients worldwide. The enormous increase in multi-drug resistant strains underscores the urgency to understand how A. baumannii evolves in hospital environments. To investigate the origin of a polyclonal outbreak of multi-drug resistant A. baumannii at the NIH Clinical Center, we determined the complete genome sequence of the three dominant strain types. Our analysis revealed that although the three outbreak strains are of the same epidemic lineage, they diverged prior to arrival to NIH. Extensive diversification had occurred since their divergence, largely mediated by homologous recombination across 20% of their genomes. Extending our analysis to international clinical isolates revealed a previously unappreciated ability of A. baumannii to vary surface molecules through horizontal gene transfer, with subsequent intra-species dissemination by homologous recombination. These findings have immediate implications in surveillance, prevention and treatment of A. baumannii infections.

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