Background & Objective: Methicillin–Resistant Staphylococcus aureus (MRSA) is one of the most important causes of hospital infections worldwide. Treatment of these infections has become more difficult because of resistance to methicillin/oxacillin and other antibiotics. The aim of this study was to determine the incidence of MRSA infections in hospitals affiliated to Hamadan University of Medical Sciences.

Materials & Methods: Seventy S. aureus clinical strains were isolated from patients from June, 2005 to June, 2006 and examined by conventional microbiological tests and PCR, respectively. Then, the antibiotic susceptibility to methicillin/oxacillin and other antibiotic were performed by Disk Diffusion Agar (DDA).

Results: The results of this study showed that Methicillin resistance gene was detected in 35 (50%) and 22 (31.4%) cases by PCR and DDA, respectively. The results of antibiotic sensitivity assays also showed there was high resistance in MRSA strains to Penicillin (100%), Cloxacillin (91.4%), Tetracycline (74.2%), Cotrimoxazole (68.6%) Erythromycin (68.5%) and Ceftazidim (51.4%). The strains of Methicillin-Sensitive Staphylococcus aureus (MSSA) showed high sensitivity results to antibiotic used, except penicillin, which all of the isolates were penicillin resistance.

Conclusion: As a conclusion, the resistant to methicillin/oxacillin in Hamadan hospitals has reached to 50% and they show multi-drug resistant.