STEC Analyses - Importance of analysis in the food industry
We have been offering PCR screening for Shiga toxin-producing Escherichia coli (STEC) at our Schönenwerd site since summer 2024. STEC are Escherichia coli (E. coli) strains with the ability to produce Shiga toxins. A synonym for Shigatoxin is Verotoxin, therefore STEC are also known as VTEC (Verotoxin producing E. coli). Illness caused by STEC can result in vomiting, diarrhoea or abdominal cramps1.
In Europe, the consumption of beef, fruit/vegetables (including sprouts), dairy products, cereals and beans is associated with STEC2.
STEC screening uses PCR to test the sample for the presence of stx1, stx2 and the eae gene. Stx1 and stx2 are the genes coding for Shiga toxin (Stx). The eae gene stands for E. coli attaching and effecting gene and encodes the major adhesion factor of STEC, intimin, a protein that promotes binding of the toxin to human intestinal epithelial cells1,3. The eae gene is distributed throughout the genus/species Escherichia coli. The sole presence of eae genes without the stx gene has no relevance to the question of STEC / VTEC.
If the stx1 and/or stx2 gene is detected, we recommend cultural confirmation, which we carry out at the National Centre for Enteropathogenic Bacteria and Listeria (NENT). Further subtyping can also be ordered if required according to the recommendations "Microbiological risk assessment of Shiga toxin-producing E. coli (STEC) in food"3.
In contrast to PCR screening, the quantitative E. coli method often fails to detect STEC / VTEC because it uses a specific enzyme that does not detect some important STEC.
We offer STEC screening for various food products, water and swabs. Please contact your account manager if you have any questions.
1 Johannes Krämer und Alexander Prange, Lebensmittel-Mikrobiologie, 8. Auflage
2 Report WHO, Shiga toxin-producing Escherichia coli (STEC) and food: attribution, characterization, and monitoring, 2018
3 Bundesamt für Lebensmittelsicherheit und Veterinärwesen (BLV), Mikrobiologische Risikoevaluation Shigatoxin produzierender E. coli (STEC) in Lebensmitteln – Grundlagen für einen Entscheidungsleitfaden zur Beurteilung von STEC-Befunden in Lebensmitteln, 2019
