Environmental Application of a Bacteriophage Cocktail Reduces Antibiotic-Resistant Escherichia coli in Poultry Litter Without Disrupting Gut Microbiota

The increasing demand for poultry meat calls for sustainable production methods that address animal welfare and combat antimicrobial resistance (AMR). Commensal Escherichia coli serve as reservoirs of resistance genes that may transfer to pathogens, facilitating AMR spread in agriculture. This study evaluated the efficacy of a bacteriophage cocktail, UPWr_E, applied as a litter spray to reduce total and antibiotic-resistant E. coli in broiler chicken rearing. The cocktail, containing four lytically active phages, was administered for four weeks. Microbiological analyses of litter, feces, and cecal contents showed a significant reduction in total E. coli by 3.2 log₁₀ CFU/g in litter and a decrease in resistant strains to gentamicin, enrofloxacin, tetracycline, and sulfamethoxazole–trimethoprim, compared to controls. No significant changes occurred in E. coli loads in feces or cecal contents, indicating limited impact on the number of commensal E. coli in cecal contents. Phages remained detectable and stable in litter and feces throughout the study. These findings demonstrate the potential of phage therapy as a targeted, environmentally friendly approach to control AMR reservoirs in poultry farming. Incorporating phage-based treatments into AMR management strategies could improve food safety and promote sustainable animal production.