Antibiotic Profile of Biofilm Producing Coagulase Negative Staphylococci Isolated from Various Clinical Specimens

Abstract

Introduction: CoNS which are normal commensal of skin and mucous membranes of human, when presented with an opportunity, are known to cause infections. The most common species among the group are the S. epidermidis. Production of extracellular slime called as biofilm help these pathogens to adhere to surfaces and protect themselves from the actions of host immune cells and chemotherapeutic agents. Objective: To identify the biofilm producing CoNS from various clinical specimens, their speciation and antibiogram. Materials and methods: 100 strains of CoNS isolated from various clinical samples were subjected to species identification by ornithine decarboxylase test, nitrate reduction test, Voges-Proskauer test, urease test, sugar fermentation tests and susceptibility to novobiocin and polymyxin B drugs. Biofilm production was detected using congo red agar and antibiotic susceptibility was tested by disc diffusion interpreted according to CLSI. Results: Out of a 100 CoNS, we speciated S. epidermidis (32%), S. hemolyticus (25%), S. hominis (14%), S. capitis, S. lugdunensis (11% each) and S. cohnii (7%). Biofilm producers were 48 in number with S. epidermidis the leading pathogen. Antibiotic susceptibility showed a multidrug resistance pattern with commonly used antibiotics such as erythromycin, ciprofloxacin and gentamicin. However, 100% sensitivities were noted for rifampicin, vancomycin and linezolid. Conclusion: Times of assuming CoNS as a non-pathogen is now in the past. Speciation of CoNS and identifying their biofilm producing abilities need to be performed alongside their antimicrobial susceptibility profiles.