Genetic Diversity of Methicillin Resistant Staphylococcus aureus in Doon Valley Hospitals

Abstract

newline newlinePresent study was conducted to determine genetic diversity of methicillin resistant S. aureus in Doon valley hospitals, Uttarakhand. A total of 300 clinical samples were collected randomly from the different age groups of patients in various hospitals in Doon Valley of Uttarakhand and were subjected to bacteriological investigations to isolate S. aureus. All confirmed S. auerus isolates were screened for methicillin resistance using phenotypic methods. The antibiotic sensitivity test by Kirby Bauer s disc diffusion method was performed followed by minimum inhibitory concentration of vancomycin through broth macrodilution method. Isolates were tested for the presence of the mecA gene and femA gene with multiplex PCR assay. PCR was also performed for detection ccrAB recombinase systems types and analysis of the protein A coding spa gene. Molecular typing by pulsed field gel electrophoresis was carried out using standard procedures. Multilocus sequence typing was conducted to characterize isolates on the basis of sequencing of internal fragments of multiple housekeeping genes. Results of the present study found that S. aureus was isolated in 111 participants. Out of 111 S. aureus isolates, 38 were methicillin resistant (MRSA). Among them, 25 were male and 13 were from female. Highest MRSA colonization rate was found among dialysis ward patients, followed by burn ward and general medical ward patients. Antibiotic susceptibility test revealed six isolates which showed resistance against vancomycin besides resistant to other antibiotics. Minimum inhibitory concentration of vancomycin further revealed six strains with a high level of resistance. These isolates were tested positive for the presence of the mecA gene, and femA gene with multiplex PCR assay. There was complete concordance in our study between the PCR results and those of phenotypic methods used to determine the presence of mecA. Presence and size of spa gene was also confirmed using PCR.