Novel integrated approach modeling proanthocyanidins and bacteriophages to combat multidrug Salmonella Typhimurium in challenged broilers

The emergence of multidrug bacterial isolates, including Salmonella ( S .) Typhimurium, which primarily spreads to humans through chicken products, is correlated with a rising prevalence of antimicrobial therapy failure. Thus, we performed a comprehensive analysis of the combined impact of Salmonella bacteriophage (BP) and grape seed oligomeric pro-anthocyanidins (GSOPs) on growth performance, immune functions, antioxidant capacity, cecal microbiota, gut integrity, and S . Typhimurium resistance in challenged broilers. A total of 250 Ross-308 male broiler chicks were offered either a control diet or a diet supplemented with Salmonella BP alone at concentrations of 10 9 PFU/0.1 ml, GSOPs alone at a level of 400 mg/kg diet, and a combination of both Salmonella BP and GSOPs, and experimentally infected with multidrug-resistant (MDR) S . Typhimurium strain at 14 days of age. Broilers administered BP, GSOPs, and their combination, particularly BP+GSOPs, had enhanced growth performance attributes even following a challenge with S . Typhimurium, alongside decreased mortality percentage, which was evidenced by increased expression of MUC-2 , β-defensin-1, cathelicidins-2, JAM -2, occludin, and CLDN-1 genes, reduced S . Typhimurium abundance, and downregulating its virulence-associated genes ( sopE and spvC ), alongside restored intestinal histological features. GSOPs+BP fortified group exhibited higher cecal beneficial bacteria counts ( Bacteroides, Firmicutes, Lactobacillus , and Bifidobacterium species), lower cecal harmful bacteria loads ( Escherichia, Enterobacteriaceae , and Clostridium clusters I and IV), decreased serum oxidative markers [H 2 O 2 , reactive oxygen species (ROS), and malondialdehyde (MDA)], and increased serum antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px)]. The incorporation of dietary BP, and GSOPs combination significantly downregulated the intestinal inflammatory regulated genes ( IL-1 β , IL-6, CCL4, CCL20, COX-2 , and iNOS ), and mTOR gene, and reduced the serum concentrations of LYZ, NO, CRP, and complement C3, alongside increased serum IgG, and IgM levels, and upregulation of autophagy-related genes ( atg5, atg7, atg12, BCLN-1 , and LC3-II ). The aforementioned beneficial effects of the BP and GSOPs combination support their prospective use in avian nutrition to enhance performance and stimulate immune defense against gastrointestinal illnesses, including S . Typhimurium infection.