Characterization of Methicillin-Resistant Staphylococcus aureus in a Tertiary Care Teaching Hospital, South India

Abstract

S. aureus causes superficial to deep seated infections in human beings. Methicillin-resistant Staphylococcus arueus (MRSA) evolved in the 1960s and since then has become a worldwide concern owing to increasing morbidity and mortality in health-care settings and even community. (MRSA) is a resistant variant of S. aureus which are resistant to beta-lactum antibiotics and other classes of antimicrobials. Early and accurate detection of MRSA and their antimicrobial susceptibility profile is therefore imperative for the selection of appropriate antimicrobial therapy. A total of 300 isolates of S. aureus collected from January 2010 to December 2012 were included in the study. S. aureus was characterized based on morphological and biochemical characters. To receive a pure culture, the isolates were grown on mannitol salt agar with supplement 5% v/v egg yolk emulsion. Antibiotic susceptibility testing was carried out on the strains by disc diffusion technique and the results interrupted according to Clinical laboratory standards International (CLSI) guidelines. A significant proportion of the S. aureus isolates were obtained from the exudates (226) specimens in all the three years followed by blood (48), urine (16) and respiratory (10). The average resistance seen in the 300 isolates tested was ampicillin (97.2%), cephelaxin (94%), cefotaxime (96.4%), cloxacillin (100%), erythromycin (82.6%), Gentamycin (76.3%), ciprofloxacin (54.4%), clindamycin (40.4%) and linezolid and vancomycin were susceptible for all the strains. In conclusion, the prevalence of MRSA in our health-care setting is 45% among the clinical isolates of S. aureus. Active screening and proper infection control procedures need to be adopted to control the MRSA infection.