Preclinical evaluation ofas a probiotic alternative against multidrug-resistant avian pathogenicin chickens.

Abstract

OBJECTIVES: Avian pathogenic(APEC) is a leading cause of disease and mortality in broiler chickens, resulting in substantial economic losses. Probiotics such as() have shown potential to enhance host immunity and limit pathogen colonization, but their efficacy against APEC is not fully understood. METHODS: One hundred diseased broilers from 20 farms were screened forisolation, serotyping, and antimicrobial resistance. The probiotic strainATS1 (GenBank accession no. PV478081.1), previously isolated and partially characterized in our laboratory, was evaluated for adhesion to Caco-2 epithelial cells, survival in murine macrophages, andeffects on growth performance, serum IgY levels, and protection against oral challenge with APEC O126:K71 at 28 days of age. RESULTS: Twenty-threeisolates were recovered, with (APEC) predominating (80%) and 20% identified as Shiga toxin-producing O26 strains. Multidrug resistance was common, including complete resistance to cefixime and aztreonam.showed strong adhesion to epithelial cells (5.65 ± 1 bacteria/cell) and survived within macrophages.supplementation increased serum IgY, improved body weight gain and feed conversion ratio, reduced cecal and hepatic APEC colonization, and lowered mortality following challenge. CONCLUSIONS: ATS1 provides protective and immunomodulatory effects against APEC by supporting intestinal colonization, surviving in macrophages, and enhancing humoral immunity. These findings highlight its potential as a probiotic strategy to improve broiler health and reduce dependence on antibiotics.