Antimicrobial susceptibility pattern of clinical isolates of methicillin resistant Staphylococcus aureus.

OBJECTIVE To study the antimicrobial susceptibility pattern of MRSA isolates from patients in a tertiary care hospital. METHODS This was in-vitro study on MRSA isolates received from clinical samples in the department of microbiology during one year (March 2004-February 2005). All samples were processed by conventional method using sheep blood agar, MacConkey's agar and Chocolate agar plates. Staphylococci were identified by catalase, coagulase and D'nase tests. Antimicrobial susceptibility testing of all isolates was performed on Mueller-Hinton agar plates by modified Kirby Bauer's Disc Diffusion method. The disc used Oxacillin (1 microg), Cephalexin (10 microg), Ofloxacin(5 microg), Fusidic acid (10 microg), Penicillin (10 microg), Vancomycin (30 microg), Erythromycin (15 microg), Gentamicin (10 microg), Teicoplanin (30 microg), Amikacin (30 microg) and Clindamycin (2 microg). RESULTS Our results indicate that out of 190 positive isolates of S. aureus, 82 (43%) were found to be MRSA. These strains were also resistant to many other antistaphylococcal antibiotics. CONCLUSION A total of 82 (43%) MRSA were isolated from various clinical samples. Pattern of first line antistaphylococcal antibiotics is changing. Antimicrobial susceptibility testing is crucial in the treatment of these patients.