Antibacterial activity of epigallocatechin gallate against Trueperella pyogenes and its potential effect on pyolysin

Trueperella pyogenes (T. pyogenes) is widely associated with suppurative infections in domestic animals and causes substantial economic losses to livestock production. With the increasing incidence of these infections and the growing prevalence of antimicrobial resistance, alternative therapeutic strategies against T. pyogenes are urgently needed. This study demonstrated that epigallocatechin gallate (EGCG), a natural product from green tea, exhibited antibacterial activity against T. pyogenes (MIC = 16-64 μg/mL; MBC = 32-64 μg/mL). At subinhibitory concentrations, EGCG inhibited bacterial growth, disrupted cellular integrity, and suppressed biofilm formation in T. pyogenes. In a mouse model, EGCG attenuated T. pyogenes infection, reduced the bacterial load in the spleen, and mitigated splenic tissue damage. Transcriptional analysis showed that EGCG at 1/2 MIC downregulated the mRNA expression of the plo gene, which encodes pyolysin (PLO), in T. pyogenes. Moreover, EGCG inhibited the hemolytic activity of T. pyogenes ATCC 19411. Molecular docking and molecular dynamics simulations further indicated a stable interaction between EGCG and PLO. Our data demonstrate the efficacy of EGCG as a potential agent in combating T. pyogenes infections and provide preliminary insight into the potential mechanism for its inhibitory effect on PLO.