Genome content determination in methicillin-resistant Staphylococcus aureus.

Staphylococcus aureus is a major pathogen responsible for both nosocomial and community-acquired infections. While the first S. aureus isolates displaying resistance to methicillin were reported in the early 1960s, endemic strains of methicillin-resistant S. aureus (MRSA) carrying multiple resistance determinants only became a worldwide nosocomial problem in the early 1980s, carrying a threefold attributable cost and a threefold excess length of hospital stay when compared with methicillin-susceptible S. aureus bacteremia. Recent efforts in the field of high-throughput sequencing resulted in the release of several MRSA genome sequences enabling the development of massively parallel tools to study clinical isolates of MRSA at the organism scale. Microarrays covering whole genomes and high-throughput sequencing devices are the two main techniques currently utilizable for whole-genome characterization. These tools not only provide information for the development of genotyping assays but also allow evaluation of potential virulence of the strains, by enumerating genetic-encoded resistance markers and toxin content. This appears particularly attractive for understanding the epidemiology of MRSA and the relationship between genome content on one side and virulence potential or epidemicity on the other side. In addition, sequence information is mandatory for the development of molecular tests allowing the rapid identification, genotyping and characterization of clinical isolates.