Broad-Host-Range Phages Isolated from Farm Environment Targeting Shiga Toxin-Producing Escherichia coli Strains

Foodborne diseases impose a considerable global burden, with Shiga toxin-producing Escherichia coli (STEC) ranking among the leading bacterial pathogens causing severe human disease. Phages represent a promising alternative for STEC control. Since cattle constitute the main reservoir of STEC, in this study, phages targeting this pathogen were isolated from cattle environments. Three phages were characterized for their host range, physicochemical stability, and antibacterial activity. These phages showed lytic activity against O157 strains, as well as against strains belonging to epidemiologically relevant non-O157 serogroups, exhibiting high efficiency of plating on several of them. The phages were stable under different physicochemical conditions and were inactivated by ultraviolet treatment. Individually, these phages significantly reduced STEC growth in liquid cultures, and a synergistic interaction was observed when they were combined into one cocktail. These findings support the development of safe and sustainable phage-based biocontrol strategies to reduce STEC contamination of foods.