Identification and characterization of <i>Escherichia coli</i> isolated from the surface water of the Laramie River, Wyoming

Surface water is vital for drinking, recreation, wildlife, agriculture, and industry, highlighting the need for routine microbiological monitoring. <i>Escherichia coli (E. coli)</i> in environmental waters serves as a key indicator of fecal contamination and is essential for monitoring water quality. We investigated the phylogenetic diversity, pathogenicity, and antimicrobial resistance (AMR) of <i>E. coli</i> strains isolated from surface water in the Laramie River watershed, used for agriculture and recreation. Phylogenetic analysis of 109 isolates identified phylogroup A as the most prevalent (74.3%), followed by E (11%), B2 (8.2%), and B1 (6.4%), indicating contamination from diverse animal and human sources. Multiplex PCR characterized 7.33% of isolates as diarrheagenic <i>E. coli</i> (DEC), with enterohemorrhagic <i>E. coli</i> (EHEC) and enteropathogenic <i>E. coli</i> (EPEC) the most frequently detected pathotypes (2.75% each). AMR analysis determined that 50.42% of isolates exhibited resistance to at least one antibiotic, with the highest resistance to tetracycline (44.4%) and ampicillin (19.6%). Multiple resistance patterns were associated with wastewater and agricultural runoff, with elevated resistance observed downstream of wastewater treatment plants. These findings provide insights into the interactions between <i>E. coli</i> diversity, pathogenicity, and AMR in the watershed, emphasizing the need for proactive water quality management to address anthropogenic impacts.