Abstract

Methicillin resistant Staphylococcus aureus (MRSA) is a main cause of nosocomial infections with consequence of increasing hospitalization, costs of treatment and rate of mortality. This study was aimed to demonstrate distribution of MRSA strains and their antibiotic resistance pattern. In this descriptive study, 185 clinical isolates of S. aureus that were collected from different infections during September 2008 to 2009 were tested by polymerase chain reaction (PCR) and micro dilution broth. All the MRSA and methicillin sensitive Staphylococcus aureus (MSSA) isolates were tested for antibiotic resistance pattern by disk diffusion method with 14 different antibiotics. Data were entered in SPSS software version 16 and analyzed by chi-square test. P value of <0.05 was considered significant. Of 185 tested S. aureus, 67(36.2%) strains were MRSA, which demonstrated 100% resistance to Penicillin, Ampicillin and CO- Amoxyclav and -80, 96.2 and 75% resistance to Cephotaxime, Nalidixic Acid and erythromycin, respectively. All S. aureusisolates was sensitive to vancomycin. All isolates with minimum inhibitory concentration (MIC) >8 µg/ml were mecA positive. MRSA is spreading worldwide with increasing levels of resistance, and accurate and early detection of these strains is encouraged.

Key words: Staphylococcus aureus, methicillin resistant Staphylococcus aureus, methicillin sensitive Staphylococcus aureus, minimum inhibitory concentration, mecA.