Staphylococcus aureus is a major cause of nosocomial infections including pneumonia, postoperative wound infection, bacteremia and other infections. A major cause of concern in the treatment of S. aureus infections is the emergence of methicillin-resistant Staphylococcus aureus (MRSA), which was reported just 1 year after the launch of methicilin. The current study was undertaken to determine the prevalence of infection caused by S. aureus in hospitalized and outdoor patients and to determine the prevalence of MRSA isolated from different clinical samples as well as to characterize the patients with MRSA on the basis of risk factors. Material and methods: The present study was conducted in the Dept. of Microbiology of a tertiary care hospital, from August 2009 to August 2011. Various clinical specimens such as pus, blood, urine cerebrospinal fluid (CSF), pleural fluid, peritoneal fluid, ascitic fluid, bile, cervical swab, semen, conjunctival swabs and ear swabs received in the Microbiology laboratory were studied. Culture was done on 4% NaCI Mueller-Hinton agar. Carriers showing MRSA were prescribed mupirocin/chlorhexidine for treatment. Further culture was done on 5-10% sheep blood agar, Mc-Conkey Agar, Mannitol salt agar and Robertson cooked meat broth. Subcultures from cooked meat broth were performed if there was no growth on primary culture plates. Results: The present study comprised of 262 S. aureus isolates from various clinical specimens. All isolates were identified as S. aureus on the basis of morphology, culture and biochemical characteristics. The current study shows that nearly 80% of the isolates were from the patients up to the age of 40 years and thereafter isolation rate decreased with age. Out of total 262 isolates included in the study, 154 (58.78%) isolates were from male patients and 108 (41.22%) were from female patients. Out of the 262 isolates, 204 (77.87%) were from pus. Isolates from urine samples comprised 22 (8.39%) followed by CSF 8 (3.05%), endocervical swab 7 (2.67%) and ear swab 7 (2.67%). Other samples included were seminal fluid 4(1.53%), sputum and throat swab 3 (1.15%), conjunctival swab 2 (0.76%). Foley\u27s tip 1 (0.38%) and umbilical tip 1 (0.38%). It was observed that in 217 (82.83%) patients infection was hospital-acquired and 45 (17.17%) patients had community-acquired infection. Conclusion: In the present study, MRSA isolation rates from ICU and wards were higher than that seen among outpatients. The most common risk factor present in most of the patients with MRSA was prolonged stay in the hospital
