PLASMID MEDIATED METHICILLIN AND VANCOMYCIN RESISTANT Staphylococcus aureus ISOLATED FROM NORTHERN INDIA

A study was conducted to determine plasmid mediated methicillin and vancomycin resistant Staphylococcus aureus along with plasmid profiling and detection of vancomycin resistance genes. This study was carried out in the Department of Microbiology and Fermentation Technology, Sam Higginbottom Institute of Agriculture Technology and Sciences, Allahabad, India. The molecular detection of gene was completed in Molecular Diagnostic Research Laboratory, Chandigarh. Clinical specimens were collected from two tertiary care hospitals of Allahabad from September 2012 to May 2013. Altogether 59 S. aureus isolates were isolated among which 20 MRSA were screened. Acridine orange in concentration of 0.1mg/ml was used for plasmid curing. Plasmid cured VRSA isolates were subjected to plasmid profiling by agarose gel electrophoresis followed by detection of vanA and vanH gene. In vitro plasmid curing of 20 methicilin resistant, one vancomycin intermediate (MIC: 8μg/ml) and three vancomycin resistant (MIC: 16-32μg/ml) strains removed resistance markers from eight MRSA and two VRSA isolates, respectively. Vancomycin resistance plasmid was successfully transferred to MSSA. Plasmid borne vancomycin resistant strains harboured 23kbp plasmid. Vancomycin resistance vanA and vanH gene was identified on molecular basis. It was concluded that plasmid mediated methicillin resistance exists less frequently but in case of VRSA, Both the mechanisms of thickening cell wall and plasmid acquisition imposed equal impact on emergence of VRSA.