Extended-spectrum β-lactamases, integrons, quinolone resistance and genetic relatedness of enteropathogenic Escherichia coli isolated from Children with diarrhea in Iran

Introduction and Objectives: This study was conducted to investigate the distribution of genes encoding integrons, extended spectrum beta-lactamase (ESBL), and resistance to fluoroquinolones in EPEC strains isolated from children with diarrhea in Iran, as well as the phylogenetic and genetic similarity among the isolates.Materials and Methods: A total of 26 EPEC isolates were collected and antibiotic susceptibility test was performed using disc diffusion method. The presence of ESBL genes (blaTEM, blaCTX-M, and blaSHV), intI, intII, and plasmid-mediated quinolone resistance (PMQR) genes was investigated by PCR. Mutations in the quinolone target genes were determined by PCR and sequencing. The phylogenetic grouping was carried out by multiplex PCR. Genetic relatedness among strains was determined by multilocus variable-number tandem repeat analysis (MLVA) method.Results: All 26 EPEC isolates were atypical. Most of the isolates were resistant to ampicillin (80.8%), trimethoprim– sulfamethoxazole (61.5%) and cefotaxime (57.7%). Overall, 15 (57.7%) isolates were identified as ESBL producers. blaTEM and blaCTX-M, intI, intII, qnrS and qnrB were detected in 46.2%, 38.5%, 53.8%, 7.7%, 26.9% and 7.7% of isolates, respectively. Both gyrA and parC mutations were present in the ciprofloxacin-resistant isolates. Phylogenetic group B1 was the most common group (46.2%), followed by A (%34.6), D (%15.4) and B2 (3.8%). Using MLVA, the EPEC isolates were categorized into 26 different types.Conclusion: Our findings showed the high prevalence of MDR and ESBL producer EPEC isolates. In addition, we identify mutations in gyrA and parC as the main mechanism of fluoroquinolone resistance. The EPEC strains were heterogeneous both phylogenetically and by MLVA typing.

کلیدواژه ها:

ESBL ، quinolone resistance ، integrons ، Genotyping ، Multi Drug Resistance (MDR) ، Food Pathogens