Exploring the impact of quercetin on the growth and biofilm formation of Leptospira interrogans.

Leptospira interrogans, the causative agent of leptospirosis, presents major challenges due to its ability to form environmental biofilms, persistent virulence, and emerging antimicrobial resistance. Plant-derived bioactive compounds offer promising alternatives to conventional antibiotics in targeting bacterial biofilms. This study investigates the antibiofilm and antimicrobial potential of quercetin, a plant-derived polyphenol, against L. interrogans. Quercetin significantly inhibited biofilm formation (91%), induced 44% biofilm dispersion at 500 µg/mL, and reduced viable cell counts by 92% at 1000 µg/mL compared to the untreated control. These effects were further validated using fluorescence-activated cell sorting (FACS), which demonstrated reduction in the live cells in the presence of quercetin. The expression levels of key genes associated with virulence and biofilm regulation were assessed using quantitative RT-PCR, revealing downregulation of csrA and upregulation of lipL32 in quercetin-treated cells. Potential molecular interactions between several leptospiral proteins and quercetin were proven through AutoDock Vina and PyMOL. These findings highlight quercetin's potential as an anti-leptospiral agent for managing leptospiral biofilm formation and dispersions.