Antimicrobial-Resistant<i>Escherichia coli</i>from Environmental Waters in Northern Colorado

Abstract

Waterborne <i>Escherichia coli</i> are a major reservoir of antimicrobial resistance (AMR), including but not limited to extended-spectrum beta-lactamase (ESBL) and <i>Klebsiella pneumoniae</i> carbapenemase (KPC) mechanisms. This study quantified and described ESBL- and KPC-producing <i>E. coli</i> in Northern Colorado from sewer water, surface water, and influent and effluent wastewater treatment sources. Total detected bacteria and <i>E. coli</i> abundances, and the percentages that contain ESBL and/or KPC, were compared between water sources. Seventy <i>E. coli</i> isolates from the various waters had drug resistance validated with a panel of 17 antibiotics using a broth microdilution assay. The diverse drug resistance observed across <i>E. coli</i> isolates was further documented by polymerase chain reaction of common ESBL genes and functional relatedness by PhenePlate assay-generated dendrograms (<i>n</i>=70). The total <i>E. coli</i> abundance decreased through the water treatment process as expected, yet the percentages of <i>E. coli</i> harboring ESBL resistance were increased (1.70%) in surface water. Whole-genome sequencing analysis was completed for 185 AMR genes in wastewater <i>E. coli</i> isolates and confirmed the presence of diverse AMR gene classes (e.g., beta-lactams and efflux pumps) in isolate genomes. This study completed surveillance of AMR patterns in <i>E. coli</i> that reside in environmental water systems and suggests a role for integrating both phenotypic and genotypic profiling beyond ESBL and KPC mechanisms. AMR screening via multiple approaches may assist in the prevention of drug-resistant <i>E. coli</i> spread from waters to animals and humans.