Occurrence and characterization of class 1 integrons in Escherichia coli from healthy individuals and those with urinary infection

Abstract

Purpose. Class 1 integrons are among the main vehicles that facilitate the spread of antibiotic-resistance genes, with serious public health consequences. The aim of this cross-sectional study was to investigate the presence of class 1 integrons and to characterize their variable regions, as well as the antimicrobial resistance profiles and phylogenetic groups of a collection of Escherichia coli isolates recovered from healthy subjects (n=42) and those with urinary infection (n=40).Methodology. The methods used included PCR, sequencing and antimicrobial susceptibility testing.Results. PCR screening for the integrase gene (intI1) revealed a higher incidence of class 1 integrons in uropathogenic E. coli (65 %, UPEC) than in commensal isolates (11.9 %). Eight of 31 intI1-positive isolates, all of them UPEC, harboured empty integrons. The variable regions of the other 23 contained gene cassettes encoding resistance to b-lactams (blaOXA-1), aminoglycosides (aadA1 and aadA5), trimethoprim (dfrA1 and dfrA17) and an ORF. To our knowledge this is the first report of an ORF identified as a putative phage tail protein associated with a class 1 integron. The aadA1 and dfrA17-addA5 arrays prevailed in commensal E. coli and UPEC, respectively. UPEC isolates were highly resistant to the antimicrobials tested, in contrast to commensal isolates. The E. coli isolates carrying gene cassettes associated with class 1 integrons were found to be unrelated to any phylogroup or multiresistance.Conclusion. Co-resistance to clinically relevant fluoroquinolone and trimethoprim-sulfamethazole in all UPEC isolates is a cause for concern. These results expand the current knowledge of gene cassettes in both commensal and pathogenic E. coli.

The Relationship of Class I Integron Gene Cassettes and the Multidrug-Resistance in Extended -Spectrum β-Lactamase Producing Isolates of Escherichia coli

“…The high frequency of MDR isolates in Kermanshah may be due to the dissemination of class I integrons in the bacteria. The correlation between MDR isolates and class I integrons has been previously reported (27). These findings emphasize the importance of integrons in the development of high resistant strains due to acquiring and expressing various resistance genes.…”

Global Evolution of Pathogenic Bacteria With Extensive Use of Fluoroquinolone Agents

“…The "integron effect" -observed also with MDR K. pneumoniae (see above) -may account for the circumstance. Class 1 integrons are common in E. coli (Copur-Cicek et al, 2014;Oliveira-Pinto et al, 2017) including ST131 isolates (Pérez-Etayo et al, 2018) and it is well-established that they are mostly associated with weak promoters (Vinué et al, 2011;Wei et al, 2013). It was demonstrated that these "weak-promoter integrons" are "low-cost structures" in E. coli and their carriage influences the fitness of the pathogen (Lacotte et al, 2017).…”

Drivers of antimicrobial resistance amongst intestinalEscherichia coliisolated from children in South Asia and sub-Saharan Africa

“…Here we present the first comprehensive AMR phenotypic data and molecular characterization for multiple antimicrobials, detecting several common mobile elements mediating the AMR including small plasmids, class I integrons with different cassettes and transposons including Tn6029, Tn10 and Tn1721 ( Fig S3). Many of the common mobile elements we detected have been reported widely in E. coli and other Enterobacteriaceae from human intestinal and extra-intestinal and animal samples [32][33][34][35][36] . Thus, while not conducted for the specific purpose of AMR surveillance, these aEPEC are likely represent a holistic overview of E. coli, and possibly other Enterobacteriaceae, in circulation at the study sites.…”