The Survey on Prevalence and Risk Factors for Antibiotic-Resistant Staphylococcus Aureus Isolated from Samples in Kashan Hospitals Moniri R1, Shafiee M2 1 Dept of Microbiology and Immunology, Kashan University of Medical Sciences, Kashan, Iran 2 Pasteur Institute of Iran, Tehran, Iran Corresponding Author's Address: Dept of Microbiology and Immunology, Kashan University of Medical Sciences, Kashan, Iran E-mail: moniri@kaums.ac.ir Received: 20 July, 2008 Accepted: 17 Nov, 2008 Background and Objective: Methicillin-resistant Staphylococcus Aureus (MRSA) is a serious problem in hospitals. The purpose of this study was to determine the prevalence and related risk factors of methicillin resistance S. aureus isolated from clinical specimens in Kashan hospitals. Materials and Methods: This descriptive study was carried out on 100 S.aureus strains isolated from patients admitted to Kashan hospitals in 2006- 2007. Strains were inoculated on blood agar containing 5% sheep blood and 7.5% mannitol salt agar media, and were incubated at 35°C for 24 hours. The isolated S. aureus strains were identified using gram staining, catalase test, coagulase tube test, growth on chrome agar and the DNAse test. The antibiotic sensitivity test was determined by disk diffusion method. Variables including age, sex, previous hospitalization, duration of hospitalization, previous antibiotic therapy, and type of the disease, were recorded in questionarres. Data were analyzed statistically by the Chi-square and Fischer’s exact tests. Results: Penicillin and Ciprofloxacin revealed the highest and lowest resistance rates respectively (99%, vs 11 %). Meticillin resistance was 22% and an intermediate resistance to Vancomycin was detected in 7% of isolates. A significant correlation was established among the presence of resistant staphylococci with age of more than 46 years old (P<0.040), previous hospitalization (P<0.000), hospitalization for more than 1 week (P<0.000), previous antibiotic therapy (P<0.004), and administration of antibiotics for more than 1 week (P<0.002). Conclusion: Awareness about the prevalence of antibiotic resistant S.aureus and identification of risk factors for infection with resistant isolates is essential to help clinicians, choosing appropriate antibiotic regimen.