Serotypes and virulence profiles of atypical enteropathogenic Escherichia coli (EPEC) isolated from bovine farms and abattoirs

Abstract

Aims: The objective of this study was to examine the prevalence of enteropathogenic Escherichia coli (EPEC) on beef and dairy farms and in beef abattoirs and to characterize the isolates in terms of serogroup and virulence markers. Methods and Results: Bovine faecal samples (n = 1200), farm soil samples (n = 600), hide samples (n = 450) and carcass samples (n = 450) were collected from 20 farms and three abattoirs throughout Ireland over a 12-month period. After selective enrichment, samples testing positive for the intimin gene (eae) using PCR screening were cultured, and colonies were examined for the presence of the eae, vt 1 and vt 2 genes. Colonies that were positive for the intimin gene and negative for the verotoxin genes were further screened using PCR for a range of virulence factors including tir, espA, espB katP, espP, etpD, saa, sab, toxB, iha, lpfA O157/OI-141 , lpfA O113 and lpfA O157/OI-154 . PCR screening was also used to screen for variations in the intimin gene (eae). Of the 2700 source samples analysed, 3Á9% (47 of 1200) of faecal, 2% (12 of 600) of soil, 6Á4% (29 of 450) of hide and 0Á7% (3 of 450) of carcass samples were PCR positive (for the presence of the eae gene). All 140 isolates obtained were atypical EPEC (aEPEC), while h and b intimin types were common. The virulence factors hlyA, tir, lpfA O113 , lpfA O157/OI-154 , and iha were frequently detected, while lpfA O157/OI-141 , saa, espA, espB and toxB were also present but to a lesser extent. Conclusions: It was concluded that cattle are a source of aEPEC, many of which have the virulence machinery necessary to be pathogenic to humans. Significance and Impact of the Study: These findings suggest the need for increased research on aEPEC with particular emphasis on food safety and public health risk.

High Prevalence of Virulence Genes in Specific Genotypes of Atypical Enteropathogenic Escherichia coli

“…Globally, there are various studies showing that aEPEC has different serogrous, such as O76 (Møller-Stray et al, 2012), O127 (Hao et al, 2012), O119, O26, and O88 (Jenkins et al, 2003). In this study, 7.4% of aEPEC isolates were O untypable, which is much lower than that reported by others (Blanco et al, 2006; Monaghan et al, 2013; Zhang et al, 2016). Blanco et al found that 110 EPEC strains were typed to 43 O serogroups and 69 serotypes with 44 new serotypes and only 13% could be assigned to classical EPEC serotypes (Blanco et al, 2006).…”

Heterogenic virulence in a diarrheagenic Escherichia coli: Evidence for an EPEC expressing heat-labile toxin of ETEC

“…Seventeen epidemiologically important variants of intimin have been reported (Blanco et al, 2005). The EPEC/ETEC strain found to carry intimin-␤ type, which was common among the aEPEC isolated from Peruvian children, diarrheal patients from Japan (Contreras et al, 2012;Wang et al, 2013) and also in bovine farms and abattoirs in Ireland (Monaghan et al, 2013). These aEPEC strains of animal origin possess essential virulence machinery to cause infection in humans also (Monaghan et al, 2013).…”

Detection of Escherichia coli O157 by Peptide Nucleic Acid Fluorescence In Situ Hybridization (PNA-FISH) and Comparison to a Standard Culture Method

“…The presence of the verotoxin genes was evaluated as previously described (21,22). Briefly, 1-ml samples of TSB cultures, grown overnight, were pelleted, and genomic DNA was extracted using the DNeasy tissue kit (Qiagen, Crawley, United Kingdom) according to the manufacturer's instructions.…”

“…Briefly, 1-ml samples of TSB cultures, grown overnight, were pelleted, and genomic DNA was extracted using the DNeasy tissue kit (Qiagen, Crawley, United Kingdom) according to the manufacturer's instructions. DNA was screened for the presence of stx 1 and/or stx 2 genes by PCR (Peltier thermal cycler [PTC-200]) using the primers and conditions previously reported (21,22). PCR products were separated by electrophoresis on a 1.5% (wt/vol) agarose gel and visualized under UV light (GelDoc 2000 system; Bio-Rad Laboratories, Hercules, CA) by ethidium bromide staining (10 mg/ml).…”