Antibiofilm action of phytochemicals on Enterobacteriaceae

Abstract

The biofilm-associated infections pose a great threat to human health. The available drugs are not effective due to the formation of biofilm and limited access to underlying pathogens. The initiation of biofilm formation occurs through adhesion, facilitated by the adhesin protein MrkD1P in the fimbriae tip. This study targeted the MrkD1P protein and employed plant phenols to inhibit biofilm formation in Escherichia coli, Salmonella typhi, and Klebsiella pneumoniae, as major Enterobacteriaceae species. A homology model was constructed for the MrkD1P protein, and 44 phenolic derivatives were assessed for their interaction with this protein. Caffeic acid and 3-hydroxybenzoic acid exhibited the best binding-free energies of 29.61 kcal/mol and 24.24 kcal/mol, respectively. Using a microtiter plates-based minimum biofilm inhibitory concentration assay, it was found that doses of these compounds ranging from 2 to 256 mg/mL effectively reduced biofilm formation. The biofilm inhibition assay demonstrated over 80 % reduction of biofilms in all tested species at inhibitory doses. Further analysis through field emission gun scanning electron micrographs revealed that the compounds disintegrated fimbriae on cell surfaces. Additionally, the re-formation assay demonstrated the inability of biofilm-associated cells to re-form the biofilm on fresh surfaces due to fimbriae inhibition. This study highlights the antibiofilm capabilities of caffeic acid and 3-hydroxybenzoic acid, indicating their potential as effective treatments for illnesses caused by Enterobacteriaceae biofilms.