Application of β-Resorcylic Acid as Potential Antimicrobial Feed Additive to Reduce Colonization in Broiler Chickens.

is one of the major foodborne pathogens that result in severe gastroenteritis in humans, primarily through consumption of contaminated poultry products. Chickens are the reservoir host of , where the pathogen colonizes the ceca, thereby leading to contamination of carcass during slaughter. A reduction in cecal colonization by would directly translate into reduced product contamination and risk of human infections. With increasing consumer demand for antibiotic free chickens, significant research is being conducted to discover natural, safe and economical antimicrobials that can effectively control colonization in birds. This study investigated the efficacy of in-feed supplementation of a phytophenolic compound, β-resorcylic acid (BR) for reducing colonization in broiler chickens. In two separate, replicate trials, day-old-chicks (Cobb500; = 10 birds/treatment) were fed with BR (0, 0.25, 0.5, or 1%) in feed for a period of 14 days ( = 40/trial). Birds were challenged with a four-strain mixture of (∼10 CFU/ml; 250 μl/bird) on day 7 and cecal samples were collected on day 14 for enumerating surviving in cecal contents. In addition, the effect of BR on the critical colonization factors of (motility, epithelial cell attachment) was studied using phenotypic assay, cell culture, and real-time quantitative PCR. Supplementation of BR in poultry feed for 14 days at 0.5 and 1% reduced populations in cecal contents by ∼2.5 and 1.7 Log CFU/g, respectively ( < 0.05). No significant differences in feed intake and body weight gain were observed between control and treatment birds fed the compound ( > 0.05). Follow up mechanistic analysis revealed that sub-inhibitory concentration of BR significantly reduced motility, attachment to and invasion of Caco-2 cells. In addition, the expression of genes coding for motility () and attachment () was down-regulated as compared to controls ( < 0.05). These results suggest that BR could potentially be used as a feed additive to reduce colonization in broilers.