Association between Antimicrobial Resistance Phenotypes and Biofilm-Associated Virulence among Clinical Isolates of Klebsiella pneumoniae

Background: Klebsiella pneumoniae is an important opportunistic pathogen increasingly associated with multidrug resistance and persistent healthcare-associated infections. Biofilm formation may enhance bacterial survival, reduce antimicrobial susceptibility, and contribute to treatment failure. This study evaluated the association between antimicrobial resistance phenotypes and biofilm-forming capacity among clinical isolates of K. pneumoniae. Materials and Methods: A prospective cross-sectional study was conducted over four months at Alluri Sitarama Raju Academy of Medical Sciences, Eluru, South India. A total of 150 non-duplicate clinical isolates of K. pneumoniae were included. Antimicrobial susceptibility testing was performed using the Kirby–Bauer disc diffusion method. Multidrug resistance, extended-spectrum β-lactamase production, and carbapenem resistance were assessed using standard phenotypic criteria. Results: Biofilm formation was detected in 115/150 (76.7%) isolates, comprising 20.7% weak, 30.0% moderate, and 26.0% strong biofilm producers. Multidrug resistance was observed in 94 (62.7%) isolates. MDR prevalence increased progressively from 40.0% among non-biofilm producers to 84.6% among strong biofilm producers (P<0.001). Biofilmpositive isolates had significantly higher odds of MDR than biofilm-negative isolates (OR 3.43; 95% CI: 1.56–7.51; P=0.002). Conclusion: A significant association was observed between biofilm-forming capacity and antimicrobial resistance among clinical K. pneumoniae isolates.