Investigating the Link Between Biofilm Formation and Antibiotic Resistance in Clinical Isolates of Acinetobacter baumannii.

Background: Acinetobacter baumannii has become a significant problem in hospitals worldwide during the last decades. Biofilm formation is a virulence factor that may affect antibiotic resistance. This study aimed to elucidate the correlation between biofilm formation and biofilm-related and oxacillinase genes in A. baumannii clinical isolates. Methods: This study was conducted on 53 A. baumannii isolates collected from hospitals affiliated with Babol University of Medical Sciences (Babol, Iran) from April to October 2023. Kirby-Bauer disc diffusion was used to determine antibacterial resistance. Biofilm formation was examined using crystal violet staining. Polymerase chain reaction was used to detect oxacillinase (bla _OXA-23, bla _OXA-24, bla _OXA-51, and bla _OXA-58) and biofilm-encoding (bap and bla _PER-1) genes using specific primers. Results: The strains showed the highest resistance to trimethoprim/sulfamethoxazole and ciprofloxacin (98.11%) and the lowest resistance to ampicillin/sulbactam (66.03%). All isolates formed biofilms. Also, 67.92%, 18.86%, and 11.32% were strong, moderate, and weak biofilm producers, respectively. The frequencies of bla _OXA-23, bla _OXA-24, bla _OXA-51, bap, and bla _PER-1 genes were 92.45%, 71.69%, 100%, 73.58%, and 58.49%, respectively. None of the isolates harbored bla _OXA-58. Conclusions: A high prevalence of antibiotic-resistant strains was found among A. baumannii clinical isolates. There was no significant correlation between the clinical sample type and biofilm formation, but a notable link was found between antimicrobial resistance and biofilm formation, except for ciprofloxacin. Oxacillinase genes were not significantly correlated with biofilm formation, but biofilm production was associated with bap rather than bla _PER-1. Understanding the A. baumannii biofilm formation process is crucial for effective control of associated infections by targeting this mechanism.