Genetic diversity of the intimin gene (eae) in non-O157 Shiga toxin-producing Escherichia coli strains in China

Xi Yang,Yanwen Xiong,Andreas Matussek,Ji Zhang,Ruyue Fan,Xiangning Bai,Shanshan Fu,Hui Sun

doi:10.1038/s41598-020-60225-w

Abstract

Shiga toxin-producing Escherichia coli (STEC) is an important foodborne pathogen. The increasing incidence of non-O157 STEC has posed a great risk to public health. Besides the Shiga toxin (Stx), the adherence factor, intimin, coded by eae gene plays a critical role in STEC pathogenesis. In this study, we investigated the prevalence and polymorphisms of eae gene in non-O157 STEC strains isolated from different sources in China. Among 735 non-O157 STEC strains, eae was present in 70 (9.5%) strains. Eighteen different eae genotypes were identified in 62 eae-positive STEC strains with the nucleotide identities ranging from 86.01% to 99.97%. Among which, seven genotypes were newly identified in this study. The eighteen eae genotypes can be categorized into five eae subtypes, namely β1, γ1, ε1, ζ3 and θ. Associations between eae subtypes/genotypes and serotypes as well as origins of strains were observed in this study. Strains belonging to serotypes O26:H11, O103:H2, O111:H8 are associated with particular eae subtypes, i.e., β1, ε1, θ, respectively. Most strains from diarrheal patients (7/9, 77.8%) carried eae-β1 subtype, while most isolates from cattle (23/26, 88.5%) carried eae-ζ3 subtype. This study demonstrated a genetic diversity of eae gene in non-O157 STEC strains from different sources in China.

Highlights

Shiga toxin-producing Escherichia coli (STEC) is a group of food-borne pathogens that can cause non-bloody diarrhea, hemorrhagic colitis (HC), and the fatal hemolytic uremic syndrome (HUS) in humans[1]
In a subset of STEC strains, intimin plays a critical role in intestinal colonization, which is encoded by the eae gene that resides on the locus of enterocyte effacement (LEE) pathogenicity island
We investigated the prevalence of eae gene and analyzed eae subtypes and polymorphisms in non-O157 STEC strains isolated from diarrheal patients, healthy carriers, animals, and raw meats in China

Summary

Introduction

Shiga toxin-producing Escherichia coli (STEC) is a group of food-borne pathogens that can cause non-bloody diarrhea, hemorrhagic colitis (HC), and the fatal hemolytic uremic syndrome (HUS) in humans[1]. In a subset of STEC strains, intimin plays a critical role in intestinal colonization, which is encoded by the eae gene that resides on the locus of enterocyte effacement (LEE) pathogenicity island. Intimin subtype β1 appears to be the most frequent among atypical EPEC strains from diarrheal patients and animals in China[16]. O157:H7 and O145:H28 serotypes are associated with the eae-γ1 subtype, whereas O26:H11 often carries eae-β1, O103:H2 and O121:H19 harbor eae-ε, and O111:H8 harbors eae-θ subtype[18] These serotypes were most frequently reported in global dysentery and HUS cases caused by STEC5. We investigated the prevalence of eae gene and analyzed eae subtypes and polymorphisms in non-O157 STEC strains isolated from diarrheal patients, healthy carriers, animals, and raw meats in China

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Results

Conclusion