TBP-TA exhibits potent antibacterial activity against vancomycin-resistant Enterococcus.

Antimicrobial resistance (AMR) exacerbates bacterial infections in different livestock species, thereby posing major challenges to animal welfare and livestock productivity. Small-molecule compounds have emerged as a promising strategy for antibacterial therapy, owing to their chemical diversity and unique mechanisms of action. In this study, we evaluated the antibacterial activity of the small-molecule compound 4-(7-(4-(diphenylamino) phenyl) benzo [c] [1,2,5] thiadiazol-4-yl)-N, N, N-trimethylbenzenaminium (TBP-TA) against vancomycin-resistant Enterococcus (VRE) through in vitro antibacterial experiments and in vivo animal models. Mechanistic investigations showed that TBP-TA compromises membrane integrity and fluidity, dissipates proton motive force, impairs efflux pump function, and triggers lethal reactive oxygen species accumulation. Untargeted metabolomics further revealed broad metabolic perturbations characterized by disruption of energy metabolism, depletion of NAD+/NADPH, and weakened antioxidant defenses. Importantly, in a mouse intestinal colonization model, TBP-TA significantly reduced VRE burdens in the jejunum, ileum, cecum, colon, and feces, achieving greater clearance than linezolid under the tested conditions. Histopathological analyses demonstrated that TBP-TA alleviated intestinal injury and improved villus architecture. These findings suggest that TBP-TA exerts potent bactericidal activity against VRE and is a promising therapeutic candidate for the treatment of multidrug-resistant bacterial infections.