Closely related coliphages infecting the multidrug-resistant Escherichia coli sequence typing 131 clone across...

Escherichia coli ST131 is a well-established multidrug-resistant clone responsible for millions of infections worldwide, particularly bloodstream and urinary tract infections. Although considerable progress has been made in elucidating the genomic evolution and characteristics of this clone, our understanding of its natural predators, bacteriophages, in the environment remains limited. This study aimed to evaluate the genomic similarities among coliphages targeting E. coli ST131, isolated from sewage samples collected in five different countries. Twenty-two E. coli ST131 strains from bloodstream infection were used for phage screening using sewage samples obtained from Bangladesh, Brazil, Saudi Arabia, Kazakhstan, and the United Kingdom. Identified phages were purified, stored, and subjected to genomic characterisation using Oxford Nanopore Technology. Genomic analyses included taxonomic classification, lifecycle assessment, phylogenetic analysis, and genome synteny comparisons. A subset of phages was further examined using transmission electron microscopy, host range assays, and broth inhibition tests. In total, 33 phages representing six distinct taxonomic groups were isolated across all sampled countries which includes the phage families Drexlerviridae, Autotranscriptaviridae, Chaseviridae, Lindbergviridae, Mktvariviridae, Sarkviridae, Lindbergviridae, and a proposed novel phage genus named Tolemanvirus. Phages from Brazil exhibited the highest genomic diversity, while those from Bangladesh, Saudi Arabia, and the United Kingdom showed notable genomic similarity. Host range analysis revealed that, although the majority of phages were specific to E. coli ST131, several were capable of infecting additional lineages, including ST95 and ST10. At higher MOIs phages achieved > 70% inhibition of bacterial growth in the selected subset of strains. These findings suggest that genetically similar phages targeting E. coli ST131 circulate globally, yet regional genomic variations may influence their host range and infection potential, potentially shaping the environmental population structure of E. coli ST131.