The Non-O157 Shiga-Toxigenic (Verocytotoxigenic)Escherichia coli; Under-Rated Pathogens

Abstract

Following a brief review of the ecology of Escherichia coli in general, the role of Shiga-Toxigenic (Verocytotoxigenic) E. coli (STEC) as pathogens is addressed. While STEC belonging to the serogroup O157 have been extensively studied and shown to be involved in many cases and outbreaks of human disease, the importance of STEC belonging to other serogroups has not been recognized as much. This review addresses the problems associated with these pathogens, demonstrating that increasing the awareness of them is a major part of the problem. This review then demonstrates how widespread isolations especially from food animals and human disease have been, discussing in particular STEC belonging to serogroups O8, O26, O103, O111, O113 and O128. The animal host-specificity of these STEC is also reviewed. In conclusion some methods of improving isolation of these pathogens is addressed.

Efa-1/LifA mediates intestinal colonization of calves by enterohaemorrhagic Escherichia coli O26 : H– in a manner independent of glycosyltransferase and cysteine protease motifs or effects on type III secretion

“…Antigen-specific humoral responses were detected and it is conceivable that they may mediate protection against natural exposure but not the high experimental challenge doses used (van Diemen et al, 2007). Given the important role of Efa-1/LifA in calf colonization, the high degree of conservation of Efa-1/LifA in non-O157 strains and the emergence of such serogroups in cattle and humans (Bettelheim 2007), further studies using multivalent vaccines or other vaccination formulae or regimens may be warranted.…”

Identification ofEscherichia coliO157 by Using a Novel Colorimetric Detection Method with DNA Microarrays

“…The 30-mer oligonucleotide probes targeting the intimin adherence protein (eae) (Zhang et al, 2002;Ramachandran et al, 2003), O157 O-antigen perosamine synthetase ( per) (Bilge et al, 1996;Reeves et al, 1996;Shimizu et al, 1999), Shiga toxin 1 (stx1), and Shiga toxin 2 (stx2) (Nataro and Kaper, 1998;Bettelheim, 2007;Serna and Boedeker, 2008) in pathogenic E. coli are shown in Table 1. The E. coli O157-specific probes were designed by using PRIMER3 software (Rozen and Skaletsky, 2000) and were purchased from Eurofins MWG Operon (Huntsville, AL) with a 5 0 -amino-C6 modification for covalent binding to the slide surface.…”

“…The rise in foodborne-related outbreaks of E. coli O157 has heightened the importance of developing improved methods to rapidly detect and characterize virulent strains (Bettelheim and Beutin, 2003;Bettelheim, 2007;Buchanan and Appel, 2010). Established culturing methods for the identification of pathogenic E. coli can be labor intensive and time consuming and assess phenotypic and genotypic markers by screening only a small number of determinants.…”

“…Future work is aimed at further development of DNA microarrays with photopolymerization by adding pathogen-specific probes for identifying virulent strains of E. coli O157 and non-O157 from distinct geographical locations and sources. The pathogen-specific probes on the expanded DNA microarrays will target several non-O157 serovars implicated in severe human disease (Brooks et al, 2005;Bettelheim, 2007;Karmali, 2009;Buchanan and Appel, 2010). Additional probes will be included to target virulence determinants that code for adhesins, proteases, cytotoxins, and effectors and that are considered to be necessary for E. coli strains to be pathogenic (Bettelheim, 2007;Karmali, 2009;Buchanan and Appel, 2010).…”

A 7-plex microbead-based immunoassay for serotyping Shiga toxin-producing Escherichia coli

“…Its variants are associated with an enhanced probability of HC and HUS (Beutin et al, 2008). Not all non-O157 STECs will cause human illness, therefore developing a rapid and highly sensitive method for identification of non-O157 STEC capable of pathogenesis would be of great benefit for regulatory agencies as well as in clinical medicine (Bettelheim, 2007).…”