Rutin Combats Salmonella Infection Through Virulence Suppression and Gut Barrier Maintenance

Salmonella Typhimurium (S. Typhimurium) is a major zoonotic pathogen that causes severe gastroenteritis and septicemia in humans and animals. While antibiotics remain the primary therapeutic approach for controlling Salmonella infections in both human and veterinary medicine, the widespread use of conventional antibiotics, which target bacterial growth or viability, exerts strong selective pressure, accelerating the emergence of resistant strains. Furthermore, the slow and costly process of developing new antibiotics is outpaced by the rapid emergence and spread of antimicrobial resistance. As a result, alternative anti-infective strategies are urgently needed. Antivirulence therapy, which targets bacterial virulence factors rather than bacterial viability, has emerged as a promising strategy to reduce the development of resistance. Using a host cell invasion assay, we identified the natural flavonoid rutin as a potent inhibitor of S. Typhimurium invasion. Notably, rutin did not significantly affect bacterial growth at concentrations that effectively inhibited invasion. Transcriptomic analysis and subsequent molecular validation demonstrated that rutin disrupts the DNA-binding activity of HilA, a critical regulator of the type III secretion system (T3SS), thereby inhibiting the expression of this key virulence factor. This disruption subsequently reduces the expression and secretion of downstream effector proteins, limiting bacterial invasiveness. Additionally, rutin significantly suppressed bacterial self-aggregation and biofilm formation, impairing the colonization ability of Salmonella. In a murine infection model, rutin treatment alleviated pathological damage and improved epithelial barrier integrity. Collectively, these findings suggest that rutin attenuates Salmonella infection through multiple mechanisms, highlighting its potential as an alternative or complementary therapeutic strategy to conventional antibiotics.