Eugenol and geraniol impede Csu-pilus assembly and evades multidrug-resistant Acinetobacter baumannii biofilms: In-vitro and in-silico evidence

Abstract

Acinetobacter baumannii forms robust biofilms, which aid protection against antimicrobials and account for adaptation in hospital settings. Biofilm formation by A. baumannii has worsens the scenario of drug resistance. Therefore, new strategies are required to tackle biofilm-forming multidrug-resistant A. baumannii. The present study investigated compounds with antimicrobials and antibiofilm properties against A. baumannii. Different antimicrobials were selected from available reports. Initially, comparative antimicrobial activity against A. baumannii isolates was assessed. Most potent antimicrobial compounds were further analyzed for time-kill kinetics, biofilm inhibition, and exopolysaccharide (EPS) reduction in their presence and absence. The antibiofilm potentials were also confirmed with SEM analysis. The relative gene expression of the csuE gene and molecular docking was carried out to investigate the molecular mechanism of mature biofilm disruption. The results demonstrated eugenol and geraniol as the most potent inhibitors with MICs of 6.08 mM and 3.24 mM, respectively, with the potential to significantly inhibit growth and EPS production. Complete inhibition of A. baumannii mature biofilms was observed with a maximum of 60.89 mM and 129.6 mM concentrations of eugenol and geraniol, respectively. The SEM analysis and lower expression of the csuE gene showed the effectiveness of potent antibiofilm agents. In-silico docking showed efficient binding of eugenol and geraniol with the csuE protein of archaic pilus. The findings of molecular docking concordant the assumption that these molecules may prevent the assembly of mature pilus, which results in abolished biofilms. In conclusion, the antibiofilm virtues of eugenol and geraniol were elucidated to be used in the future to control the persistence of biofilm-forming drug-resistant A. baumannii.