Extended Spectrum β-Lactamase Activity and Cephalosporin Resistance in Escherichia coli from US Mid-Atlantic Surface and Reclaimed Water

Phylogenetic distribution and extended spectrum beta-lactamase (ESBL) activity of Escherichia coli recovered from surface and reclaimed water in the midAtlantic U.S. were evaluated. Among 488 isolates, phylogroups B1 and A were the most and least prevalent, respectively. Water type, but not season, affected phylogroup distribution. The likelihood of detecting group A isolates was higher in reclaimed than pond (P < 0.01), freshwater river (P < 0.01) or brackish river (P < 0.05) water. Homogeneity in group distribution was lowest in pond water, where group B1 comprised 50% of isolates. Only 16 (3.3%) isolates exhibited phenotypic resistance to one or more cephalosporins tested and only four had ESBL activity, representing groups B1, B2 isolates, and D. Phylogroup was a factor in antimicrobial resistance (P < 0.05), with group A (8.7%) and D (1.6%) exhibiting the highest and lowest rates. Resistance to cefoxitin was the most prevalent. Multi- versus single drug resistance was affected by phylogroup (P < 0.05) and more likely in groups D and B1 than A which carried resistance to cefoxitin only. The most detected beta-lactam resistance genes were bla(CMY-2) and bla(TEM). Water type was a factor for bla(CTX-M) gene detection (P < 0.05). Phenotypic resistance to cefotaxime, ceftriaxone, cefuroxime and ceftazidime, and genetic determinants for ESBL-mediated resistance were found predominantly in B2 and D isolates from rivers and reclaimed water. Overall, ESBL activity and cephalosporin resistance in reclaimed and surface water isolates were low. Integrating data on ESBL activity and beta-lactam resistance among E. coli populations can inform decisions on safety of irrigation water sources and One Health. IMPORTANCE Extended spectrum beta-lactamase (ESBL) producing bacteria, that are resistant to a broad range of antimicrobial agents, are spreading in the environment but data remain scarce. ESBL-producing Escherichia coli infections in the community are on the rise. This work was conducted to assess presence of ESBL-producing E. coli in water that could be used for irrigation of fresh produce. The study provides the most extensive evaluation of ESBL-producing E. coli in surface and reclaimed water in the mid-Atlantic United States. The prevalence of ESBL producers was low and phenotypic resistance to cephalosporins (types of beta-lactam antibiotics) was affected by season but not water type. Data on antimicrobial resistance among E. coli populations in water can inform decisions on safety of irrigation water sources and One Health.

Automated summary

The phylogenetic distribution and ESBL activity of Escherichia coli from surface and reclaimed water in the mid-Atlantic U.S. were evaluated. The prevalence of ESBL producers was low and cephalosporin resistance was affected by season but not water type.