Global Clones of Escherichia coli CTX-M-15/ST10 and CTX-M-65/ ST683 Isolated from Brazilian Recreational Freshwater

TL;DR

This study identifies two drug-resistant E. coli strains in Brazilian freshwater, highlighting the environment's role in spreading antibiotic resistance.

Contribution

First report of E. coli ST10 in Brazilian rivers and ST683 with blaCTX-M-65 in Brazil.

Findings

Two MDR ESBL-producing E. coli strains were isolated from a Brazilian river and waterfall.

The strains belong to globally disseminated clones ST10 and ST683, with resistance to multiple antibiotics.

The presence of ESBL genes blaCTX-M-15 and blaCTX-M-65 indicates clinical relevance and environmental spread.

Abstract

The emergence of antimicrobial resistance (AMR) poses a critical global health threat, underscoring the interconnectedness of human, animal, and environmental health within the One Health framework. This study describes two multidrug-resistant (MDR) extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli strains, classified as critical priority bacteria by the World Health Organization, identified in recreational freshwater in Brazil. A cross-sectional study was conducted to investigate the presence of ESBL-producing Enterobacterales in water samples from a river in a touristic Brazilian city, including the waterfall, stream, and areas outside the city center. Bacteria were cultured and isolated on MacConkey agar supplemented with ceftriaxone, identified by MALDI-TOF, and antimicrobial susceptibility testing was performed by disk diffusion. ESBL-producing strains were then subjected to whole-genome sequencing and bioinformatic analysis. Two ESBL-producing E. coli strains were recovered from the waterfall (USP-MG-W) and steam (USP-MG-B). These strains showed an MDR profile, with resistance to β-lactams, tetracyclines, aminoglycosides, quinolones and phenicols, but remained susceptible to carbapenems. USP-MG-B and USP-MG-W harbor the ESBL genes blaCTX-M-15 and blaCTX-M-65, respectively, highlighting their broad-spectrum cephalosporin resistance and clinical relevance. Predicted heavy metal resistance genes suggest AMR co-selection. USP-MG-B belongs to pandemic E. coli sequence type (ST) 10, closely related to Brazilian human isolates. At the same time, USP-MG-W is part of clonal complex 155 (ST683), associated with international livestock and poultry strains. Remarkably, this study is the first report of E. coli ST10 in Brazilian rivers and ST683 with blaCTX−M−65 in Brazil. The detection of ESBL clones in freshwater underscores the role of the environment as a reservoir of critical priority pathogens. These findings highlight the urgent need for a One Health approach to the AMR crisis and for strengthening the epidemiological surveillance of ESBL-producing Enterobacterales beyond human settings.

The online version contains supplementary material available at 10.1007/s00284-026-04790-9.

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