STEC, EHEC and pathogenic E. coli O157

Shigatoxigenic group of Escherichia coli ('STEC')

Some species of Escherichia coli (E. coli) have the potential to be pathogenic to humans. Among these are the shigatoxigenic group of E. coli (known as STEC or VTEC). These are E. coli which produce shiga toxins (also known as verotoxine). These proteins are described by the Stx genes (Stx1 and/or Stx2) and may produce symptoms ranging from simple diarrhoea to hemorrhagic diarrhoea.

Performing molecular biology assays which target specific E. coli Stx genes can enable the reliable detection of such STEC.

Click here to view information about GeneDisc plates for detection of pathogens in food.

Enterohemorrhagic group of Escherichia coli ('EHEC')

Among these STEC, some bacteria may be lethal to humans, especially infants under five years old. The bacteria not only produce the shiga toxin (Stx gene) but they can also attach to the intestinal wall because of the protein Intimin (an adhesine) coded by the eae gene. The E.coli carrying these two genes (Stx and eae) have previously been identified as being responsible for Uremic and Haemolytic Syndrome (UHS). They are commonly known as Entero-Hemorrhagic Escherichia coli (EHEC).

These EHEC have been described by the EFSA (European Food Safety Association) which has published details of the top five pathogenic strains of E. coli identified in food-borne pathogen outbreaks. They are E. coli which carry the Stx and eae genes among the following serogroups: E. coli O157:H7, E.coli O145, E. coli O111, E. coli O103 and E. coli O26.

E. coli O157:H7, like the other E. coli in the top five are EHEC, and pathogenic only if they carry the Stx and eae genes.

What Solution Can Pall Offer?

Developed for use as part of the GeneDisc Rapid Microbiology System, Pall offers GeneDisc plates for detection of pathogens in food, including both STEC and EHEC.

As the GeneDisc plates for detection of pathogens in food target these pathogenic strains of E.coli O157, they reduce the number of false-positives (non-pathogenic E.coli).

Pall has developed the first comprehensive molecular diagnostics test that enables:
  • Rapid detection of pathogenic E.coli O157:H7 and STEC non-O157
  • Identification of the top five STEC with their virulence factors
After an enrichment phase of eight to sixteen hours, a GeneDisc plate for STEC indicates the presence of pathogenic E. coli (Stx & eae) and also direct detection of pathogenic E. coli O157. A GeneDisc plate for EHEC then enables confirmation if the serotype of E. coli is among the top five if required.

Thanks to the easy-to-use GeneDisc Rapid Microbiology System, this rapid test may be carried out either onsite or within service laboratories. Please contact usfor a list of available laboratories.

Published Articles

 Poster: Direct, rapid, reliable detection of EHEC with the GeneDisc System (BfR/AFSSA, 2007)
 Article: Monitoring verotoxigenic E. coli & identification of human pathogenic VTEC (EFSA, 2007)
 Poster: Real-time PCR assay for detection of STEC/identification of EHEC (BfR/AFSSA, 2008)1
1 Presented at IAFP Annual Meeting, July 2008