Abstract
The emergence and dissemination of resistance to third- and fourth-generation cephalosporins among Enterobacteriaceae from different sources impose a global public health threat. Here, we characterized by whole-genome sequencing four Escherichia coli strains harboring the blaCTX–M–65 gene identified among 49 isolates from beef and pork collected at retail. The genomic content was determined using the Center for Genomic Epidemiology web tools. Additionally, the prediction and reconstruction of plasmids were conducted, the genetic platform of the blaCTX–M–65 genes was investigated, and phylogenetic analysis was carried out using 17 other genomes with the same sequence type and harboring the blaCTX–M–65 gene. All strains harbored blaCTX–M–65, blaOXA–1, and blaTEM–1B, and one also carried the blaSHV–12 gene. Other resistance genes, namely, qnrS2, aac(6′)-Ib-c, dfrA14, sul2, tetA, and mphA, were present in all the genomes; the mcr-1.1 gene was identified in the colistin-resistant strains. They belong to sequence type 2179, phylogenetic group B1, and serotype O9:H9 and carried plasmids IncI, IncFIC(FII), and IncFIB. All strains share an identical genetic environment with IS903 and ISEcp1 flanking the blaCTX–M–65 gene. It seems likely that the blaCTX–M–65 gene is located in the chromosome in all isolates based on deep in silico analysis. Our findings showed that the strains are clonally related and belong to two sub-lineages. This study reports the emergence of CTX-M-65-producing E. coli in Portugal in food products of animal origin. The chromosomal location of the blaCTX–M–65 gene may ensure a stable spread of resistance in the absence of selective pressure.
Highlights
Bacteria harboring antimicrobial resistance genes can be spread to humans, constituting a global public health concern (O’Neill, 2016)
From 49 isolates of E. coli phenotypically resistant to thirdgeneration cephalosporins, a total of 10 different bla genes were identified in 42 ESBL and seven PMAβ producers: blaCTX−M−1 (n = 8), blaCTX−M−15 (n = 5), blaCTX−M−27 (n = 2), blaCTX−M−55 (n = 1), blaCTX−M−9 (n = 1), blaCTX−M−14 (n = 7), blaCTX−M−32 (n = 9), blaCTX−M−65 (n = 4), blaSHV−12 (n = 5), and blaCMY−2 (n = 7)
Four CTX-M-65-producing E. coli were identified among 49 ESBL/PMAβ producers isolated from meat
Summary
Bacteria harboring antimicrobial resistance genes can be spread to humans, constituting a global public health concern (O’Neill, 2016). Extended-spectrum β-lactamase (ESBL) is a group of enzymes that hydrolyze oxymino-beta-lactam antibiotics, Clonal Spread of CTX-M-65 E. coli Producers conferring resistance to a wide variety of β-lactams, including penicillins, first-, second-, third-, and fourth-generation cephalosporins, and monobactams (Bush, 2018). These enzymes can be inhibited by β-lactam inhibitors such as clavulanic acid, sulbactam, and tazobactam through the covalent link to the serine residue active site (Tooke et al, 2019). In Portugal, the CTX-M-1, CTX-M-14, and CTX-M-32 variants were reported as the most prevalent in commensal and pathogenic E. coli isolated from food-producing animals and food products (Clemente et al, 2019; Silva et al, 2019)
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