BIOFILM PRODUCTION AND ITS CORRELATION WITH ANTIBIOTIC RESISTANCE IN COAGULASE-NEGATIVE STAPHYLOCOCCI ISOLATED FROM A TERTIARY CARE HOSPITAL IN EASTERN INDIA

Background: Coagulase-negative staphylococci (CoNS), long dismissed as culture contaminants, are increasinglyrecognised as clinically significant opportunistic pathogens, particularly in hospitalised patients, immunocompromised hostsand device-associated infections. Their capacity to form biofilm contributes to bacterial persistence, recurrent infection andreduced antimicrobial susceptibility. The objective is to determine the frequency of biofilm production among clinicallysignificant CoNS isolates and to assess its association with antibiotic resistance in a tertiary care hospital in eastern India.Materials and Methods: This hospital-based cross-sectional study was conducted in the Department of Microbiology,MGM Medical College & LSK Hospital, Kishanganj, Bihar, from January 2025 to December 2025. A total of 350 nonduplicate,clinically significant CoNS isolates from various clinical specimens were studied. Identification and speciationwere performed by standard microbiological methods. Biofilm production was detected by the Congo Red Agar method.Antimicrobial susceptibility testing was performed by the Kirby–Bauer disc diffusion method and interpreted per CLSIguidelines; methicillin resistance was detected using a cefoxitin disc. Multidrug resistance (MDR) was defined as nonsusceptibilityto at least one agent in three or more antimicrobial categories. Associations were tested using the chi-squaretest (Yates' correction for 2 × 2 tables) or Fisher's exact test, with p < 0.05 considered significant. Results: Of 350 isolates,215 (61.4%) produced biofilm; 85 (24.3%), 74 (21.1%) and 56 (16.0%) were strong, moderate and weak producers,respectively. Staphylococcus epidermidis was the commonest species (133; 38.0%), followed by S. saprophyticus (75;21.4%) and S. haemolyticus (61; 17.4%). Overall, 254 (72.6%) isolates were methicillin-resistant CoNS (MR-CoNS) and290 (82.9%) were MDR. Methicillin resistance was significantly more frequent among biofilm producers than nonproducers[182/215 (84.7%) vs 72/135 (53.3%); OR 4.83, 95% CI 2.92–7.97; p < 0.001], as was MDR [191/215 (88.8%) vs99/135 (73.3%); OR 2.89, 95% CI 1.64–5.12; p < 0.001]. Among individual agents, biofilm production was associated withcefoxitin (p < 0.001) and ciprofloxacin resistance (p = 0.014), and inversely associated with rifampicin resistance (12.6% vs23.0%; OR 0.48, 95% CI 0.27–0.85; p = 0.016). All isolates were susceptible to vancomycin; linezolid and teicoplaninretained high activity. Conclusion: Biofilm production was common among clinically significant CoNS isolates and wassignificantly associated with methicillin resistance and MDR. Routine biofilm detection alongside susceptibility testing mayhelp guide antimicrobial therapy and strengthen infection-control practice in tertiary care settings.