Prevalence of Methicillin Resistance and Some of Virulence Genes in Clinical Isolates of Staphylococcus aureus

BACKGROUND AND OBJECTIVESStaphylococcus aureus is one of the most important pathogens that produces a wide range of toxins and plays a role in causing disease in the host. The aim of this study was to identify prevalence of virulence genes and antibiotic resistance patterns among different clinical isolates of S. aureus.MATERIALS AND METHODSIn this cross sectional and descriptive study, clinical isolates of S. aureus were collected from three referral hospitals in Sari city and identified by using Standard biochemical tests. To determine the antibiotic resistance pattern, Kirby-Bauer disk diffusion method and minimum inhibitory concentration (MIC) were conducted. All isolates were screened for mecA, enterotoxin A (SEA), enterotoxin B (SEB) and Alpha‑hemolysin (HLA) genes. Statistical correlations were carried out.RESULTS AND DISCUSSIONA total of ۱۱۲ S. aureus isolates were identified, which were subjected to antimicrobial susceptibility testing. A total of ۶۷ (۵۹.۸%) strains were found to be MRSA isolates which were cefoxitin MIC of >۴ μg/ml and resistant to methicillin. The highest frequency of antibiotic resistance was observed against erythromycin in ۶۱ isolates (۹۱%) and clindamycin in ۴۸ isolates (۷۱.۶%) the lowest resistance was against in norfloxacin ۹ isolates (۱۳.۴%) and amikacin in ۱۴ isolates (۲۰.۹%). MRSA isolates showed ۱۰۰ and ۰% resistance to cefoxitin and vancomycin, respectively. mecA genes were present in all MRSA isolates. HLA was found in ۳۷.۳% of MRSA isolates. SEA genes were detected in ۲۳.۸% MRSA isolates while the SEB gene recovered from only ۲.۹% MRSA isolates.CONCLUSIONThe results illustrated the diversity of antibacterial resistance and toxin gene profiles among MRSA isolates. The increased prevalence of methicillin-resistant S. aureus isolates containing virulence genes and antibiotic resistance genes is a serious threat for the hospitalized patients. The results showed that the relationship between virulence genes and antibiotic resistance pattern can be considered as an important issue.

کلیدواژه ها:

Alpha‑hemolysin ، enterotoxin A ، enterotoxin B ، mecA ، Staphylococcus aureus ، MRSA.