E. coli, despite being among the organisms most commonly isolated in clinical microbiology laboratories, remains poorly understood by many regarding its within-species phylogenetic diversity, lineage-specific virulence and antimicrobial resistance capabilities, host specificity (or lack thereof), and ecology. This session will describe the three broad pathotypes of E. coli (commensal, diarrheagenic, and extraintestinal pathogenic), focusing on the latter group, i.e., ExPEC. Attendees will gain an appreciation of the implications of E. coli population structure for emerging antimicrobial-resistant and virulent E. coli clonal groups, source tracking (including of foodborne resistant strains), rapid diagnostics, and novel preventative measures.