CTX-M-Producing Bacteria Isolated from a Highly Polluted River System in Portugal

Abstract

Enterobacteriaceae resistant to third-generation cephalosporins are a great concern for public health, as these are first-line drugs to treat infections. The production of carbapenemases and extended spectrum beta-lactamases (ESBLs) and/or the overexpression of AmpC β-lactamases are the main mechanisms of resistance to these antibiotics. Among the ESBLs, CTX-M β-lactamases are the most prevalent worldwide. Our aims were to determine the prevalence of cefotaxime-resistant Enterobacteriaceae along a heavily polluted river and characterize blaCTX-M carriers. River water was collected in 11 sites along the main course and tributaries, in two sampling moments. Water quality was evaluated and a collection of cefotaxime-resistant isolates was obtained. blaCTX-M carriers were characterized regarding phylogenetic affiliation, clonality, antibiotic susceptibility, gene diversity, and context. Water presented very low quality in all sites. From 147 cefotaxime-resistant isolates, 46% carried blaCTX-M and were affiliated with Escherichia, Klebsiella, Enterobacter, and Citrobacter. Molecular typing revealed clonal isolates in different sites and over the two years, suggesting survival of the strains in the river or continuous pollution inputs from the same sources. Eight variants of blaCTX-M were found, with blaCTX-M-15 being the most prevalent (52.5%). Sites with a lower water quality showed the highest resistance rates and prevalence of blaCTX-M, suggesting that river water may embody human health risks.

Phylogenetic group distribution and antibiotic resistance of <i>Escherichia coli</i> isolates in aquatic environments of a highly populated area

“…The presence of bla CTX-M genes in water is often associated with highly self-transferable plasmids, indicating the transfer of ESBL-producing E. coli from sewage to rivers [47] . The most common ESBL gene identified in our study was bla CTX-M-15 (32/56, 57%), which is consistent with recent studies conducted in South Africa and Portugal and with studies in Lebanon covering estuaries, wells, springs, and rivers [16] , [21] , [48] , [49] . This frequency is higher than that shown in Thailand (44.7%) [50] , but a higher prevalence was reported in Tunisia (85%) and Germany (81%) [51] , [52] .…”

Screening of Antimicrobial Resistance in Bacterial Isolates from Red Sea Coast in Jeddah, Saudi Arabia

“…The investigation done by [19], which focused on samples gathered from the Lis River, yielded results that were incongruent with the findings of our own study. The sensitivity test for cefotaxime (CTX) and chloramphenicol (C) yielded a cefotaxime (CTX) sensitivity rate of 98% and a chloramphenicol (C) sensitivity rate of 25%.…”

“…Regarding the Gentamicin (CN) sensitivity test, the obtained yield of 31% closely aligns with our own findings. In the [19] investigation, samples were obtained from the river water, including locations proximal to areas characterized by pollution and the discharge of sewage. This disparity in findings may potentially be attributed to these factors.…”

Unseen Weapons: Bacterial Extracellular Vesicles and the Spread of Antibiotic Resistance in Aquatic Environments

“…The most common blaCTX-M variant is blaCTX-M-15 . Sites with poorer water quality exhibit higher resistance rates and blaCTX-M prevalence, suggesting potential risks to human health associated with river water contamination [ 70 ]. Likewise, in a study conducted along three sites on the Tigris River, Iraq, 40 out of 67 bacterial isolates were identified as E. coli using the Vitek2 diagnostic method.…”