Isolation, characterization, and application of the novel polyvalent bacteriophage vB_EcoM_XAM237 against pathogenic Escherichia coli.

A novel polyvalent broad-spectrum phage, vB_EcoM_XAM237 (XAM237), was isolated from pig farm sewage. It can simultaneously lyse multiple strains of pathogenic Escherichia coli (E. coli), demonstrating a broad host range. When the enteropathogenic E. coli (EPEC) strain E711 was used as the host bacterium, the phage XAM237 exhibited a short latent period, high stability at different temperatures and pH values and good tolerance to chloroform. Moreover, phage XAM237 can efficiently adsorb and lyse host bacteria in vitro. Whole-genome sequencing revealed that XAM237 is a double-stranded DNA (dsDNA) phage consisting of 170 541 bp with a G + C content of 35%. Phylogenetic analysis confirmed that XAM237 belongs to the family Straboviridae, genus Tequatrovirus. In addition, the genome of XAM237 did not contain genes related to lysogenicity, virulence or antimicrobial resistance. The effects of phage XAM237 in treating EPEC infections in vivo were evaluated in a mouse model. Phage XAM237 was able to reduce the number of colonized aEPEC strain E711 in the small intestine, liver, spleen, and kidney. This study suggested that phage XAM237 may be a promising candidate biologic agent for controlling pathogenic E. coli infections.