Methicillin-resistant S. aureus in Eastern India: Some Molecular Epidemiological Perspectives

Abstract

Background: Staphylococcus aureus is the most important nosocomial pathogen causing skin and soft tissue infection. Methicillin-resistant S. aureus (MRSA) is now established in both community-acquired and hospital-acquired infections. The defining feature of MRSA is the staphylococcal cassette chromosome mec (SCCmec), which is a mobile genetic element, carrying the central determinant for broad-spectrum beta-lactam antibiotic resistance encoded by the mecA gen, whereas the presence of panton-valentine leukocidin (PVL) gives more virulence to the MRSA. Aim: To assess molecular epidemiology of MRSA in Eastern India. Design: Descriptive cross-sectional study. Materials and Methods: In this study, from 940 samples in a tertiary care hospital in rural India, over 6 months, 20 MRSA isolates were identified. These isolates were typed to study the diversity in the structures of SCCmec elements and ccr types. Statistical analysis was performed by SPSS software. Results: Isolates carrying SSCmec Type IV were found to be dominant (60%), whereas a small proportion was SSCmec Type V (10%). Some composite strains were found. PVL gene was found to be associated with community-associated MRSA (CA-MRSA) genotypes. Conclusion: Genotypical blurring of CA-MRSA and hospital-acquired MRSA was seen. Composite SCCmec strains found showing need for new nomenclature methods.