Staphylococcus aureus Comparative Database
In 2005, Staphylococcus aureus killed more people in the U.S. than did AIDS/HIV (Klevens et al., 2008). Despite the importance of this emerging pathogen, full genome sequence is available for only a very limited subset of the broad genetic diversity and genomic variation found in S. aureus. To address this emerging public health threat, the Broad Institute will sequence 46 S. aureus genomes to provide needed and unique genomic resources to Staphylococcus researchers. This project has two main foci:
- Evolution of the 80/81-USA200 group and the genomics of pandemic spread. The clinical significance of the USA200 MRSA (methicillin resistant S. aureus) clone is increasing in scope worldwide. The USA200 clone actually represents the re-emergence of an older, pandemic MSSA clone that was widespread in the 1950s, and subsequently disappeared a decade later when methicillin was used to treat these infections. We will sequence forty strains that span both the 1960s epidemic, and the USA200 epidemic that began in the late 1990s. These strains represent a global sample of diversity from ten countries. This will provide an in-depth understanding of how pandemic clones evolve both spatially and through time. In addition, this collection can be compared to other MRSA genomes to identify genetic determinants that might be implicated in pandemic spread.
- Genomic mosaicism as an evolutionary response to anthropomorphic influences. We have identified a clinically significant hybrid group of S. aureus, composed of the closely related ST34, and which has been identified through genome-wide multi-locus sequence typing as a hybrid of ST10/145 and ST30. In ST34, a contiguous region, comprising roughly ten percent of the genome is derived from the ST10/145 parent. A second mosaic group, ST42, is a mosaic, with the ST10/145 parent contributing roughly twenty percent of the genome, but the major parent is ST39. To understand the age and the genetic changes associated with hybridization, we will sequence representatives of ST10, ST34, ST42, and ST145.
- D. Ashley Robinson, Department of Microbiology, University of Mississippi Medical Center.