Background: Staphylococcus aureus remains one of the most important agents of community- and hospital-acquired infections, and its capacity to acquire antimicrobial resistance together with the ability to form biofilm poses a major therapeutic challenge. This study was undertaken to determine the antimicrobial resistance pattern and biofilm-forming ability of S. aureus isolated from clinical samples of patients attending a tertiary care hospital in Bareilly, Uttar Pradesh, India.
Methods: A hospital-based cross-sectional study was conducted in the Department of Microbiology, Rajshree Medical Research Institute, Bareilly. A total of 500 clinical samples received from indoor and outdoor patients were processed by standard microbiological methods. Antimicrobial susceptibility testing was performed by the Kirby–Bauer disc diffusion method as per CLSI guidelines, methicillin resistance was detected using the cefoxitin disc diffusion test, and biofilm production was assessed by the microtiter plate method.
Results: Of the 500 clinical samples processed, 59 (11.8%) yielded bacterial growth, of which 51 (86.4%) were identified as S. aureus. The isolates showed the highest resistance to penicillin and ampicillin (88.2% each), while all isolates (100%) remained sensitive to linezolid. Twenty-eight isolates (54.9%) were methicillin-resistant S. aureus (MRSA). Multidrug resistance (resistance to ≥3 antibiotic classes) was observed in 47 (92.2%) isolates. All 51 isolates produced biofilm in vitro, of which 13 (25.5%), 24 (47.1%), and 14 (27.5%) were weak, moderate, and strong biofilm producers, respectively. Strong biofilm producers retained the highest sensitivity to linezolid, gentamicin, and tetracycline.
Conclusion: A high prevalence of methicillin resistance, multidrug resistance, and biofilm production was observed among clinical S. aureus isolates in this tertiary care hospital. Linezolid, gentamicin, and tetracycline remain reliable therapeutic options. Regular antimicrobial surveillance and an institutional antibiotic stewardship programme are warranted to guide empirical therapy and curb the further spread of resistant strains.