Abstract
BackgroundDiarrheagenic Escherichia coli (DEC) is one of the most important etiological agents of diarrheal diseases. In this study we investigated the prevalence, virulence gene profiles, antimicrobial resistance, and molecular genetic characteristics of DEC at a hospital in western China.MethodsA total of 110 Escherichia coli clinical isolates were collected from the First Affiliated Hospital of Chengdu Medical College from 2015 to 2016. Microbiological methods, PCR, antimicrobial susceptibility test, pulsed-field gel electrophoresis and multilocus sequence typing were used in this study.ResultsMolecular analysis of six DEC pathotype marker genes showed that 13 of the 110 E. coli isolates (11.82%) were DEC including nine (8.18%) diffusely adherent Escherichia coli (DAEC) and four (3.64%) enteroaggregative Escherichia coli (EAEC). The adherence genes fimC and fimH were present in all DAEC and EAEC isolates. All nine DAEC isolates harbored the virulence genes fyuA and irp2 and four (44.44%) also carried the hlyA and sat genes. The virulence genes fyuA, irp2, cnf1, hlyA, and sat were found in 100%, 100%, 75%, 50%, and 50% of EAEC isolates, respectively. In addition, all DEC isolates were multidrug resistant and had high frequencies of antimicrobial resistance. Molecular genetic characterization showed that the 13 DEC isolates were divided into 11 pulsed-field gel electrophoresis patterns and 10 sequence types.ConclusionsTo the best of our knowledge, this study provides the first report of DEC, including DAEC and EAEC, in western China. Our analyses identified the virulence genes present in E. coli from a hospital indicating their role in the isolated DEC strains’ pathogenesis. At the same time, the analyses revealed, the antimicrobial resistance pattern of the DEC isolates. Thus, DAEC and EAEC among the DEC strains should be considered a significant risk to humans in western China due to their evolved pathogenicity and antimicrobial resistance pattern.
Highlights
Diarrheagenic Escherichia coli (DEC) is one of the most important etiological agents of diarrheal diseases
Prevalence of DEC among 110 E. coli strains In order to investigate the prevalence of DEC, we categorized the clinical E. coli (n = 110) isolates into different DEC pathotypes based on the PCR results for virulence marker genes
These results suggest the existence of a certain incidence of DEC at this hospital in western China
Summary
Diarrheagenic Escherichia coli (DEC) is one of the most important etiological agents of diarrheal diseases. The bacterium Escherichia coli is one of the most important etiological agents of diarrheal diseases. DEC consist of six major pathotypes: enteroaggregative E. coli (EAEC), enterohemorrhagic E. coli (EHEC; e.g., Shiga toxin-producing E. coli, STEC), enteropathogenic E. coli (EPEC), enteroinvasive E. coli (EIEC), enterotoxigenic E. coli (ETEC), and diffusely adherent E. coli (DAEC) [5]. EAEC is characterized by the presence of the transcriptional activator gene aggR and/or the serine protease precursor gene (pic) and/or the enteroaggregative heat stable toxin 1 (EAST-1) gene (astA). EPEC is characterized by the presence of the intimin gene (eae) and/or the bundle forming pili gene (bfp). The product of the eae gene enables attachment and effacement on intestinal epithelial cells, while bfp is encoded on the EPEC adherence factor (EAF) plasmid. Similar to most DEC characterized, DAEC carries two F1845 fimbrial adhesion genes (daaD and/or daaE), which are highly conserved and probably involved in the virulence mechanism [2, 7, 8]
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