Isolation and Characterization of a Lytic Phage vB_EcoS_GZMU_E2010: A Promising Candidate against Clinical Multidrug-Resistant Escherichia coli.

The global escalation of bacterial antimicrobial resistance, particularly in Escherichia coli, constitutes an urgent public health threat. Bacteriophages represent a promising therapeutic arsenal against multidrug-resistant pathogens, underscoring the necessity of acquiring additional phages to expand phage libraries. In response to multidrug-resistant E. coli, this study isolated a lytic phage, designated E. coli phage vB_EcoS_GZMU_E2010. This phage demonstrated effective lytic activity against pathogenic E. coli strains, that included Extended-Spectrum β-Lactamase-producing E. coli (ESBL-E. coli) strains. The time-kill kinetics and terminal growth suppression data illustrate that, bacteriophage vB_EcoS_GZMU_E2010 exhibits potent antimicrobial action across a wide range of MOIs (from 0.001 to 1000). Transmission electron microscopy revealed that phage exhibits a siphovirus-like morphology within class Caudoviricetes, featuring a long noncontractile tail and icosahedral capsid. Whole-genome sequencing identified a 44,255 bp circular double-stranded DNA genome with 50.81% GC content. Comparative genomics revealed <95% whole-genome nucleotide identity to all reported phages, with the closest relative (Escherichia phage hz69, GenBank accession: ON556632.1) sharing only 90.7% identity, establishing its taxonomic novelty. Following a 60 min latent period, the phage entered a rapid burst phase characterized by exponential titer increase. Viral progeny release plateaued at 80 min postinfection. Bacteriophage vB_EcoS_GZMU_E2010 exhibited high stability across temperature (4-50 °C) and pH (4-10) gradients. Comprehensive screening confirmed the absence of antibiotic resistance genes and virulence factors. Besides, the maximum inhibition rate of this bacteriophage on biofilm reached 73.5%. Collectively, these findings position phage vB_EcoS_GZMU_E2010 as a promising candidate for combating drug-resistant infections, providing a potential strategy against multidrug-resistant E. coli pathogenesis.