Molecular characterization and antimicrobial susceptibility of the CA-MRSA isolated from healthcare workers, Tehran, Iran.

INTRODUCTION Methicillin resistant Staphylococcus aureus (MRSA) has become as a nosocomial pathogen worldwide. Considering the importance of MRSA typing for understanding the evolution and dissemination of these strains, we studied the molecular characteristics of MRSA colonized healthcare workers (HCWs). METHODOLOGY All MRSA isolated from HCWs, were genotyped using staphylococcal cassette chromosome mec (SCCmec) with multiplex PCR assay, multilocus sequence typing (MLST) and spa typing. Then antibiotic susceptibility pattern and presence of pvl genes were evaluated in MRSA isolates. RESULTS Cluster analysis by eBURSTv3 showed that MRSA isolates belonged to two major clonal complexes (CC); CC88 (ST88, ST825, ST859) and CC30 (ST39, ST2, ST24) and five singletons. The most prevalent SCCmec type was type IV (70.59%) followed by type V (29.41%). Totally 11 different spa types were discriminated among which type t186 was predominant. All of the MRSA tested (100%) were susceptible to teicoplanin, linezolid and fusidic acid. Totally 52.94% of isolates were positive for pvl genes. CONCLUSIONS The ST88-MRSA-IV accounted for most colonized MRSA isolates. We documented a different molecular epidemiology of MRSA nasal colonization in hospitals under studied, due to the introduction of epidemic clones (ST88, ST39, ST2235, ST80, ST813, ST398, ST825, ST24, ST22, ST859 and ST2).