Deciphering the twinning act of antimicrobial resistance and biofilm-associated virulence in multidrug-resistant...

Acinetobacter baumannii has emerged as a predominant healthcare-associated pathogen, exhibiting high levels of antibiotic resistance and biofilm-forming capability, contributing to its persistence in hospital environments. This study evaluated the association between antibiotic resistance and biofilm-associated genes in A. baumannii clinical isolates. A total of 247 A. baumannii isolates were collected from a tertiary care hospital in Chennai, India, over three years (March 2023-January 2025). Antibiotic susceptibility testing revealed multi-drug resistance (MDR), particularly to carbapenems and β-lactam/β-lactamase inhibitors, while colistin and tigecycline remained effective against all isolates. Biofilm formation assays demonstrated that 82.8 % of isolates exhibited biofilm-producing capabilities, with 46.2 % categorized as strong biofilm producers. Molecular characterization confirmed the widespread presence of antibiotic resistance genes, including bla_OXA-51 and ISAba1 (100 %) and bla_OXA-23 (97.05 %), along with genes associated with quinolone, aminoglycoside, and tetracycline resistance. Virulence gene analysis revealed the high prevalence of biofilm-associated genes (pgaA-D, csuA-E, ompA and bap), indicating their role in bacterial adherence and persistence. Statistical analysis revealed a significant association between MDR and biofilm-forming ability in the isolates. These findings offer region-specific molecular epidemiological insights and underscore the need for ongoing surveillance and enhanced infection control strategies.