Characterization and Antimicrobial Efficacy of a Bacteriophage Targeting Multidrug-Resistant Escherichia coli

The emergence of multidrug-resistant (MDR) Escherichia coli poses a significant threat to global public health, necessitating alternative therapeutic strategies. In this study, we isolated and characterized a novel lytic bacteriophage (phage), vB_EcoM_51, from poultry farm sewage and evaluated its potential against MDR E. coli. Transmission electron microscopy revealed that the phage exhibits morphological features typical of the Myoviridae family, including a polyhedral head (∼66.62 nm) and a contractile tail (∼97.32 nm). Genome analysis indicated a double-stranded DNA virus of 167,016 bp with a GC content of 35.54%, classifying it within the Tequatrovirus genus. The phage showed potent lytic activity against eight E. coli strains and one Salmonella enterica strain. Stability assessments revealed broad thermal tolerance (-20 to 50 °C) and broad pH stability (pH 2-11). One-step growth kinetics analysis indicated rapid replication, with a latent period of 5 min and a burst size of approximately 212 plaque-forming units (PFU) per infected cell. In a mouse model infected with E. coli, phage treatment at 1 × 10⁹ PFU significantly improved survival rates, reduced bacterial loads in organs, and attenuated inflammatory responses. Collectively, these findings demonstrate that phage vB_EcoM_51 represents a promising candidate for phage therapy against MDR infections.