A Phage Collection Propagated in <i>Escherichia coli</i> K-12 Shows Broad Lytic Activity Against a Diverse Panel of Multidrug-Resistant Isolates

Background: Bacteriophages offer potential solutions against drug-resistant bacteria. However, a comprehensive evaluation of their efficacy against a collection of human-derived clinical strains has not been performed. Materials and Methods: We constructed a collection of 42 phages hosted by Escherichia coli K-12 and determined their lytic spectra against 144 clinical, predominantly multidrug-resistant E. coli strains. Results: Principal component analysis based on the lytic spectra revealed three clusters that roughly corresponded to the phylogenetic classification of the phages. This analysis also identified clinical strains that were resistant to various phages. We identified phage ΦWec277, which was capable of infecting 78.5% of the E. coli clinical strains. Conclusions: The exceptionally broad host range of ΦWec277 suggests its potential for pre-emptive phage therapy against E. coli infections. However, tailored phage approaches are needed to address phage-resistant strains. These findings provide insights into the opportunities and challenges for future phage therapy applications.