To determine antimicrobial susceptibility and biofilm production among coagulase negative staphylococci at a tertiary care hospital

Abstract

CoNS are gaining importance due to increase in resistance rates to betalactam antibiotics and multi drug resistance. Although specific virulence factors are not as clearly established, it seems clear that factors such as bacterial polysaccharide components, and ability to form biofilm are involved in attachment and/or persistence of bacteria on foreign materials. Biofilms usually result in persistent infections that cannot be easily resolved with standard antibiotic treatments; therefore, the biofilm formation ability and the resistance to antimicrobial therapy can be intimately related. A prospective cross-sectional study was done on purely isolated CoNS from various clinical samples from both out patients and inpatients. All the test strains were subjected to antimicrobial susceptibility testing. The ability to produce biofilm was detected by tube adherence method. Among 193 CoNS isolates 156 were from inpatients and 37 were from out patients. Methicillin resistant was seen in 80.31%. Of the total, 40.41% showed moderate biofilm formation by tube adherence method. 23.32% of isolates did not form biofilm. All the isolates from blood samples showed moderate (20/26) and strong (6/26) biofilm formation. Among non biofilm producers 66.67% were MS CoNS isolates and 33.33% were MRCoNS. 94.59% of biofilm producers were MRCoNS and 5.41% were MSCoNS. Production of biofilm was relatively more (1.16) among CoNS isolates of IPD than OPD. As Coagulase negative Staphylocooci are exhibiting multi drug resistance and are able to form biofilm, these organisms causing a major challenge for the physicians. Hence, such problems can be prevented by detection of biofilm producers and appropriate antibiotic doses modification. The issue of antibiotic resistance among CoNS needs to be addressed through a more rational use of existing antibiotics as well as the development of new antimicrobial agents.