Antimicrobial resistance and molecular typing of diarrheagenic Escherichia coli among patients with foodborne diarrhea in Xi’an City in 2021

Abstract

ObjectiveTo investigate the infection status， pathogenic types， antimicrobial resistance and molecular typing of diarrheagenic Escherichia coli （DEC） isolated from patients with foodborne diarrhea in Xi’an City in 2021.MethodsFecal samples from patients with diarrhea were collected from 5 sentinel hospitals for DEC isolation and the pathogenic types of DEC were confirmed via PCR to detect virulence genes. Antimicrobial susceptibility testing and molecular typing were performed using the broth microdilution method and pulsed field gel electrophoresis （PFGE）. The results were statistically analyzed using SPSS software 19.0.ResultsAmong the 389 fecal samples collected from patients with diarrhea， 40 were DEC-positive， with a positivity rate of 10.28%. A total of 41 DEC strains were identified in this study. Enterotoxigenic E. coli （ETEC） and enteroaggregative E. coli （EAEC） were predominant， accounting for 41.46% （17/41） and 39.02% （16/41） of cases， respectively. The gene types estIa/estIb （70.59%， 12/17） and astA/pic （87.50 %， 14/16） were dominant in ETEC and EAEC， respectively. Forty strains （97.56%， 40/41） were resistant to at least one antibiotic， and the resistance rates to ampicillin， tetracycline， cefotaxime， and nalidixic acid were greater than 50%. The multidrug resistance rate was 56.10% （23/41）. Cluster analysis revealed 40 PFGE patterns from the 41 DEC strains. The similarity of these patterns was 62.0%-100.0%.ConclusionThe detection rate of DEC in patients with foodborne diarrhea in Xi’an City in 2021 was relatively high， with the major pathotypes being ETEC and EAEC. The PFGE patterns of the strains were diverse. Finally， the antimicrobial and multidrug resistance of the strains was relatively severe.

Keywords

• diarrheogenic escherichia coli
• virulence gene
• antimicrobial resistance
• pulsed field gel electrophoresis
• foodborne pathogens