Protective effects of sanguinarine-baicalin salt in broilers challenged with avian pathogenic Escherichia coli O78.

Avian pathogenic Escherichia coli (APEC) O78 causes acute colibacillosis in broilers and contributes to mortality, impaired growth, and multi-organ injury. This study evaluated the in vitro antibacterial activity and in vivo protective effects of sanguinarine-baicalin salt (SBS) in broilers subjected to an acute systemic APEC O78 challenge. Minimum inhibitory concentration (MIC), bacterial growth, and biofilm formation were assessed in vitro. In vivo, broilers were intraperitoneally challenged with APEC O78 on days 11-13 and treated with dietary SBS at 5-320 mg/kg diet from day 14. Survival, growth performance, organ injury, serum biochemical and inflammatory indices, intestinal morphology, jejunal gene expression, cecal microbiota, and exploratory hepatic proteomic responses were evaluated. The MIC of SBS was 256 μg/mL, compared with 32 μg/mL for amoxicillin. SBS delayed bacterial growth but did not significantly inhibit biofilm formation under the tested conditions. In vivo, SBS improved survival, with the 20 mg/kg diet group showing the lowest treatment-period mortality. The 20-40 mg/kg diet range generally produced the most favorable overall responses, including improvements in growth performance, liver and spleen indices, and serum ALT, CREA, UA, and inflammatory cytokines. SBS treatment was also associated with improved intestinal morphology, increased transcription of barrier-related genes, reduced transcription of TLR4/NF-κB-related inflammatory genes, and changes in cecal microbial composition. Exploratory hepatic proteomics revealed APEC-associated alterations and treatment-associated shifts involving proteins related to cellular stress, redox homeostasis, tissue structure, and hepatic lipid and energy metabolism. Overall, dietary SBS showed protective effects against acute systemic APEC O78 challenge, accompanied by systemic, hepatic, and intestinal host responses.