Genotyping of Staphylococcus aureus strains among healthcare workers and patients in the tertiary referral Children's Medical Hospital in Tehran, Iran.

Nasal carriage among hospital personnel is an important source of nosocomial staphylococcal infection. Therefore, this study aims to evaluate Staphylococcus aureus nasal colonisation among healthcare workers (HCWs) and its association with infection in children through analysis of antibiotic susceptibility profiles and genetic similarity. Nasal swabs were taken from the anterior nares of HCWs and also a total of 130 strains that had been isolated from various clinical samples were examined. Antibiotic susceptibility profiles of the strains were determined using the disc-diffusion technique and genotyping was performed by amplification of the enterobacterial repetitive intergenic consensus sequences (ERIC-PCR). Approximately 48% of clinical strains obtained were methicillin-resistant S. aureus (MRSA), whereas only 24.7% of strains from HCWs were MRSA. Among isolates from HCWs, cephalothin, cefazolin, chloramphenicol, rifampicin and vancomycin were most effective, with susceptibility rates of 100%. In this study, the ERIC-PCR profiles did not reveal any genetic similarity among the S. aureus strains from HCWs and the clinical samples. In contrast, MRSA strains showed clonal dissemination, with clones D and A2 predominant among patients and HCWs, respectively. No association was observed between the MRSA nasal carriers and infections in patients. These findings suggest that MRSA nasal carriage among HCWs may not be the source of related infections in the group studied.