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Comparative genomic analysis of community-acquired ST80-SCCmec IV Staphylococcus aureus isolates by high-density microarray

Abstract number: o115

Goering  R.V., Larsen  A.R., Skov  R., Tenover  F.C., Anderson  K., Dunman  P.M.

Objectives: 

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) isolates producing Panton-Valentine leucocidin (PVL) are now a worldwide concern. In Europe, ST80-SCCmec IV (ST80-IV) isolates are the predominant concern while, in the United States, these strains have appeared as pulsed-field types USA400 (ST1-SCCmec IV) and more recently described USA300 (ST8-SCCmec IV). To better understand the European situation, we compared the genomic content of ST80-IV isolates with other MRSA strains by high-density microarray analysis.

Methods: 

The genomic composition of two ST80-IV isolates was assessed using Affymetrix S. aureus GeneChips (Affymetrix, Santa Clara, CA). Purified chromosomal DNA from each isolate was queried by hybridization for the presence or absence of the 7775 loci represented on the chip. These included resistance determinants, exoenzymes, exo- or enterotoxins, and a variety of virulence regulators and cell surface factors. The results were compared to microarray data recently obtained for S. aureus USA100, 300, 400 and 500 isolates (Tenover, et al., J. Clin. Microbiol., in press, 2005).

Results: 

Overall, the ST80-IV isolates were 97% related, differing primarily in conserved hypothetical open reading frames and intergenic sequences. In general, ST80-IV isolates were more similar to USA400 than to USA300 isolates. For example, both ST80-IV and USA400 isolates appear to share the same capsular polysaccharide synthesis type and agr type. However, important differences between these two strains were observed as in the case of fibronectin-binding proteins A and B (fnbA and fnbB), which were absent from USA400 but present in ST80-IV isolates. Analysis of all loci suggested the presence of gene combinations potentially important in facilitating the persistence and spread of these strains in a community environment.

Conclusion: 

High-density microarray analysis related ST80-IV isolates more closely to other community-acquired, rather than hospital-acquired, MRSA–consistent with clinical experience. The similarities and differences noted between these and other epidemic MRSA strains represent an important resource for identifying gene combinations specific to ST80-IV isolates. These data should help in strain identification, epidemiological analysis, and in providing a greater understanding of the mechanisms by which clonal lineages such as ST80-IV persist and spread in the community setting.

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Subject:
Location: Oxford, UK
Presentation type:
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