STEC

Shiga Toxin producing E coli. A group of pathogenic E coli including 0157 and the other variants of the ‘big 6.’

For more information upgrade to premium membership and see E coli 0157 Micro Data Profile. Please also refer to the excellent blog by Roy Betts of Campden BRI at (and snippet below) E. coli vs. Shiga toxin-producing E. coli – what’s the difference and what’s the problem? from Campden BRI

STEC are a group of E. coli that contain genes coding for the “Shiga toxin” (stx) which is also known as Verocytotoxin. Although E. coli O157 is the most well-known of this group, many hundreds of STEC serogroups exist and all have the potential to cause human illness. Some strains can also attach to the gut wall, causing an even more severe illness.

If STEC are consumed within a food, they will begin to multiply when they reach the gut. Those that can attach to the gut wall will do so potentially causing the first primary symptom of severe STEC infection: haemorrhagic colitis or severe bloody diarrhoea. If that isn’t bad enough, the Shiga toxin produced by this organism can enter the bloodstream and potentially cause kidney damage, leading to haemolytic uremic syndrome. These severe symptoms often result in hospitalisation and, in the worst cases, death.

The infective dose for STEC is known to be very low. The ingestion of just ten cells is believed to cause illness. The low infective dose together with its symptoms make person-to-person spread between those that are ill and healthy individuals possible – unless great care is taken with personal hygiene.

What about non-O157 STEC organisms?

Whilst the O157 serogroup is still the major cause of STEC-related illnesses in many countries, it’s now clear that there are a wide range of other serogroups that have caused serious outbreaks. As a result, various countries have taken measures to test for, and prevent the sale of, contaminated products. For example, in the USA there is a legal requirement to test various beef cuts for STEC serogroups O26, O45, O103, O111, O121 and O157, as it’s now recognised that they have all caused, or have the potential to cause, serious illness. In the EU, manufacturers of sprouted seeds have a legal requirement to test seeds destined for sprouting or sprouted seed irrigation water for STEC serogroups O157, O26, O103, O111, O145 and O104:H4. Any samples found positive may not be placed on the market.

Our views on STEC are changing as the reliance we have on specific pathogenic serogroups is challenged. It comes as recent outputs from the European Food Safety Authority (EFSA) state that any STEC regardless of serogroup has the potential to cause severe illness. In the future we will not be looking for certain serogroups but for the presence of any STEC as a major safety risk.