Supplementary file 1_4-Hydroxycoumarin inhibits biofilm formation and enhances antibiotic efficacy against Escherichia coli O157:H7.docx

This study aimed to identify compounds capable of modulating LuxS/AI-2-related phenotypes and to evaluate their potential to disrupt biofilms and enhance antibiotic efficacy against E. coli O157.</p>Methods<p>The effects of 4-HC on biofilm formation, extracellular polymeric substance (EPS) biosynthesis, and flagella-mediated motility were assessed in vitro.

Antibiotic potentiation was evaluated through combination assays across multiple antibiotic classes. In vivo efficacy was tested in a murine systemic infection model, with qualitative histological observation used to evaluate splenic, hepatic, and ileal tissue damage.</p>Results<p>4-HC disrupted biofilm formation by suppressing EPS biosynthesis and flagella-mediated motility, thereby destabilizing biofilm architecture and impairing bacterial dissemination. 4-HC acted as a broad-range potentiator for most antibiotics tested, with the most pronounced effect observed in combination with fosfomycin sodium.