Prevalence ofagrSpecificity Groups AmongStaphylococcus aureusIsolates From University Hospitals in Tehran

The accessory gene regulator (agr) quorum sensing system of Staphylococcus aureus controls the expression of most of the genes encoding extracellular virulence factors. The aim of this study was the investigation of genetic polymorphism of the agr locus in S. aureus isolates and the possible relationship between agr groups and infection types. In a total of 212 S. aureus strains isolated, antibiotic susceptibility was determined and agr specific groups were identified by multiplex PCR. The majority of isolates belonged to agr group I (55.1%), followed by agr group II (16.9%), agr group III (16.5%), and agr group IV (9.4%). Although agr group I was very prevalent in all specimens, agr-specific group II was dominant in nasal swabs (30%), agr-specific group III was prevalent in respiratory tract specimens (26%), and agr-specific group IV was higher in cutaneous specimens(12.1%). The association between agr specific groups and type of infections were not statistically significant. These results will be helpful in verifying the characteristic of S. aureus strains in Middle East countries.