Genomic and Phylogenetic Analysis of E. coli O157:H7: Toward Improved Surveillance and Public Health Response.

Escherichia coli O157:H7 is a major foodborne pathogen responsible for severe illnesses, including hemolytic uremic syndrome. Despite existing public health efforts, recurrent outbreaks persist, highlighting gaps in our understanding of its genetic variability and transmission dynamics. Genomic insights into its evolutionary characteristics are essential for improving diagnostic and surveillance strategies. This study employed next-generation sequencing (NGS) and phylogenetic analysis to examine E. coli O157:H7 isolates obtained from three hospitals in Edo State, Nigeria. DNA was extracted and sequenced using validated protocols, and sequences were analyzed through established bioinformatic pipelines. Phylogenetic trees were constructed to determine evolutionary relationships, while comparative genomic analysis was conducted to identify virulence and antimicrobial resistance genes. The results revealed substantial genetic heterogeneity among the isolates, with clustering patterns corresponding to geographical origins. Conserved virulence genes such as stx1 and stx2 were present across most strains, while variation in accessory genomes suggested adaptive evolution. Several isolates demonstrated genetic similarity to known outbreak strains and exhibited markers of antimicrobial resistance. These findings suggest that the pathogen remains highly adaptable, with significant potential for persistence and dissemination across different environments. The results underscore the need to integrate genomic data into routine public health surveillance to track pathogen evolution and inform targeted interventions. Strengthening molecular diagnostic capacity and enhancing food safety regulations will be critical for early outbreak detection and response. This study contributes valuable genomic data on E. coli O157:H7 in a sub-Saharan African context and provides a foundation for precision guided public health strategies.