Prevalence, Antimicrobial Resistance, and Whole Genome Sequencing Analysis of Shiga Toxin-Producing Escherichia coli (STEC) and Enteropathogenic Escherichia coli (EPEC) from Imported Foods in China during 2015-2021.

Jinling Shen,Shuai Zhi,Xuebin Xu,Dehua Guo,Lina Zhao,Jingzhang Lv,Yuan Jiang

doi:10.3390/toxins14020068

Abstract

Shiga toxin-producing Escherichia coli (STEC) and enteropathogenic Escherichia coli (EPEC) are foodborne pathogens that cause hemolytic uremic syndrome and fatal infant diarrhea, respectively, but the characterization of these bacteria from imported food in China are unknown. A total of 1577 food samples from various countries during 2015–2021 were screened for STEC and EPEC, and the obtained isolates were tested for antimicrobial resistance and whole genome sequencing analysis was performed. The prevalence of STEC and EPEC was 1.01% (16/1577) and 0.51% (8/1577), respectively. Antimicrobial resistances to tetracycline (8%), chloramphenicol (8%), ampicillin (4%), ceftazidime (4%), cefotaxime (4%), and trimethoprim-sulfamethoxazole (4%) were observed. The antimicrobial resistance phenotypes corresponded with genotypes for most strains, and some resistance genes were related to mobile genetic elements. All 16 STEC isolates were eae negative, two solely contained stx1 (stx1a or stx1c), 12 merely carried stx2 (stx2a, stx2d, or stx2e), and two had both stx1 and stx2 (stx1c + stx2b, stx1a + stx2a + stx2c). Although they were eae negative, several STEC isolates carried other adherence factors, such as iha (5/16), sab (1/16), and lpfA (8/16), and belonged to serotypes (O130:H11, O8:H19, and O100:H30) or STs (ST297, ST360), which have caused human infections. All the eight EPEC isolates were atypical EPEC; six serotypes and seven STs were found, and clinically relevant EPEC serotypes O26:H11, O103:H2, and O145:H28 were identified. Two STEC/ETEC (enterotoxigenic E. coli) hybrids and one EPEC/ETEC hybrid were observed, since they harbored sta1 and/or stb. The results revealed that food can act as a reservoir of STEC/EPEC with pathogenic potential, and had the potential ability to transfer antibiotic resistance and virulence genes.

Highlights

Shiga toxin-producing E. coli (STEC) are major foodborne pathogens, which can cause watery diarrhea, bloody diarrhea, or hemorrhagic colitis, and even life-threatening hemolytic uremic syndrome (HUS)
A total of 16 (1.01%) food samples were confirmed to be contaminated with Shiga toxin-producing Escherichia coli (STEC), and 8 (0.51%) food samples contaminated with enteropathogenic Escherichia coli (EPEC) (Table 1)
Multidrug-resistant isolates harboring the respective multiple antimicrobial resistance genes, which are related to mobile genetic elements, were identified, and have the potential to transfer antibiotic resistance

Summary

Introduction

Shiga toxin-producing E. coli (STEC) are major foodborne pathogens, which can cause watery diarrhea, bloody diarrhea, or hemorrhagic colitis, and even life-threatening hemolytic uremic syndrome (HUS). It is estimated that STEC leads to 2,801,000 acute illnesses, 3890 HUS cases, and 230 deaths worldwide [1]. According to the U.S Center for Disease and Control, an estimated 265,000 STEC infections, 3600 hospitalizations, and 30 deaths occur each year in the United States [2]. In China, the pathogenic E. coli bacteria have emerged and the human illnesses caused by these bacteria increased gradually each year from 2010 to 2019, and at present they rank 5th among all major foodborne pathogens. It is worth noting that, among the emerging pathogenic E. coli, STEC infections increased most markedly [3]. STEC has been isolated from various foods, and is commonly found in retail meats in China [4,5]

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