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), vBEcoM₅1, 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 vBEcoM₅1 represents a promising candidate for phage therapy against MDR infections.