Indian Journal of Microbiology Research

Staphylococcus aureus remains as one of the most potent bacterial human pathogen because of its expression of various virulence factors and also due to its property of multidrug resistance. A total of 468 non-duplicate S.aureus strains obtained from various clinical specimens were included in the study. Methicillin Resistant S.aureus (MRSA) strains were screened for DNase production using DNase agar, hemolytic property of the isolates were detected in 5% sheep blood agar plates, hemagglutination property of the isolates were demonstrated using 1% O group RBC's, slime production was detected using congo red agar medium and biofilm production was quantitatively assayed by microtitre plate method. Antimicrobial susceptibility profile was studied for the MRSA isolates. Out of 468 S.aureus strains, 114(24%) strains were detected as MRSA. Among the MRSA strains 99(86%) were positive for DNase, 77(67%) were showed beta hemolysis, 49 (42%) strains were positive for hemagglutination, 70 (61%) were slime producers, most of the strains were biofilm producers, 4(3.5%) were non-adherent, 85(74%) were weakly adherent, 23(20%) were moderately adherent and 2(1.7%) were strongly adherent. About 56%, 60% and 63% of the isolates were resistant to cotrimoxazole, erythromycin and ciprofloxacin respectively and about 22% and 33% of the isolates showed resistance towards clindamycin and gentamicin respectively. All the isolates were sensitive to vancomycin, teicoplanin and linezolid. About 10(8.7%) strains showed high level mupirocin resistance (HLMR) and 1(0.8%) strain showed low level mupirocin resistance (LLMR). Both HLMR and LLMR (100%) strains showed susceptibility to fusidic acid. MRSA infections remain a major threat in both community and nosocomial settings. Therefore a thorough understanding of its virulence mechanisms and regular surveillance of antimicrobial susceptibility pattern will help the clinician to choose appropriate treatment options and to control the emergence of multidrug resistant strains.