A STUDY OF BIOFILM FORMATION AND METHICILLIN RESISTANCE IN COAGULASE NEGATIVE STAPHYLOCOCCUS IN VARIOUS CLINICAL SAMPLES

Coagulase negative Staphylococcus, always regarded as nonpathogenic common commensal of skin and mucous membrane, are emerging as ubiquitous endemic nosocomial and oppurtunistic pathogens in recent times. They usually are considered as culture contaminants, thus left untreated which lead to their increased pathogenic potential. Methicillin resistance in Coagulase negative Staphylococcus is of significant concern as these strains are also multi drug resistant. The purpose of this study was to estimate the frequency of Methicillin resistance in CoNS in clinical samples and determine their biofilm producing ability and in-vitro antimicrobial susceptibility. A total of 2240 various clinical samples like urine, pus, blood, swabs received during one year period from January to December 2023 were processed in clinical laboratory, Department of Microbiology, Andhra Medical College, King George Hospital, Visakhapatnam. CoNS were isolated and identified by biochemical reactions and methicillin resistant strains identified by cefoxitin and oxacillin disc diffusion method and tested for biofilm production by Congo red agar and tissue culture plate method. Antimicrobial susceptibility done by conventional Kirby Bauer disk diffusion method.326 isolates (14.5%) were identified as CoNS, biofilm production was seen in 109 of 326 strains (33.4%), methicillin resistance in 46 of 326 (14.1%). The highest percentage of MRCoNS was observed in urine samples 124 of 326 (38%). All the isolates were sensitive to Linezolid. Emergence of MR in CoNS poses a major health concern due to injudicious use of antibiotics which lead to increased growth rate of antimicrobial resistance in CoNS.