Open Access Research article

Genetic structure of community acquired methicillin-resistant Staphylococcus aureus USA300

Ryan Tewhey123, Christopher R Cannavino456, John AD Leake45, Vikas Bansal1, Eric J Topol12, Ali Torkamani12, John S Bradley45* and Nicholas J Schork12*

Author affiliations

1 Scripps Genomic Medicine, Scripps Translational Science Institute, La Jolla, CA, USA

2 Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, USA

3 Division of Biological Sciences, University of California, San Diego, La Jolla, CA, USA

4 Department of Pediatrics, Division of Infectious Diseases, Rady Children’s Hospital San Diego, San Diego, CA, USA

5 Department of Pediatrics, Division of Infectious Diseases, University of California, San Diego, CA, USA

6 Department of Pediatrics, Division of Hospital Medicine, Rady Children’s Hospital San Diego, San Diego, CA, USA

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Citation and License

BMC Genomics 2012, 13:508  doi:10.1186/1471-2164-13-508

Published: 25 September 2012

Abstract

Background

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is a significant bacterial pathogen that poses considerable clinical and public health challenges. The majority of the CA-MRSA disease burden consists of skin and soft tissue infections (SSTI) not associated with significant morbidity; however, CA-MRSA also causes severe, invasive infections resulting in significant morbidity and mortality. The broad range of disease severity may be influenced by bacterial genetic variation.

Results

We sequenced the complete genomes of 36 CA-MRSA clinical isolates from the predominant North American community acquired clonal type USA300 (18 SSTI and 18 severe infection-associated isolates). While all 36 isolates shared remarkable genetic similarity, we found greater overall time-dependent sequence diversity among SSTI isolates. In addition, pathway analysis of non-synonymous variations revealed increased sequence diversity in the putative virulence genes of SSTI isolates.

Conclusions

Here we report the first whole genome survey of diverse clinical isolates of the USA300 lineage and describe the evolution of the pathogen over time within a defined geographic area. The results demonstrate the close relatedness of clinically independent CA-MRSA isolates, which carry implications for understanding CA-MRSA epidemiology and combating its spread.