Community- and Health Care-Associated Methicillin-Resistant Staphylococcus aureus Infection in Tehran, Iran: Comparison of Drug Resistance and Virulence Determinants

Background: Methicillin-resistant Staphylococcus aureus (MRSA) can cause serious infections not only in hospitals but also in the community. The present study was aimed to characterize drug resistance and virulence determinants of community-associated (CA) MRSA isolate compared with healthcare-associated (HA) MRSA. Materials and Methods: A total of 44 patients with HA-MRSA and 11 patients with CA-MRSA infection (median age, 72 years) were included. The clinical isolates of MRSA were subjected to molecular analysis of virulence genes and drug susceptibility testing. Results: Panton-Valentine leucocidin (PVL) exotoxin and toxic shock syndrome toxin (TSST) genes were disproportionately distributed between CA- and HA-isolates. PVL genes were more likely to be found among CA-isolates (36.4%) than HA-isolates (18.2). TSST genes were identified in only 2 CA-MRSA isolates tested (18.2%) compared with 9 HA-isolates (20.5%). Exfoliative toxin- b gene was negative in all isolates, however, one HA-isolate was positive for exfoliative toxin-a. mec-A gene was present in all clinical isolates. CA-isolates were more likely to be susceptible to trimethoprim-sulfamethoxazole and vancomycin compared with HA-isolates. Vancomycin-intermediate resistance was found in 2 HA-isolates. All clinical isolates were also resistant to clindamycin. Conclusions: CA- and HA- MRSA isolates are epidemiologically and microbiologically distinct. Thus, the strategies to prevent and treat these infections would be different. Patients with CA- and HA-MRSA infections should be treated effectively and receive follow-up evaluation to ensure the resolution of their infection. Surveillance studies should be conducted to determine the extent of CA- and HA-MRSA dissemination in Iran.