Verotoxin

Enterobacteriaceae of the species E. coli are part of the intestinal flora of healthy humans, as well as many farm animals. Therefore, they are indicators of fecal contamination of water and food. Due to various pathogenicity factors, often plasmid-coded or which are transmitted by phages, E. coli has to be considered as facultative pathogenic.

E. coli is able to produce two cytotoxins, verotoxin 1 and 2. Due to the similarities of the verotoxins to the shiga-toxin of the shigella dysentery, they have also been labelled as the shiga-like toxin 1 and 2 (SLT-I and SLT-II, also stx 1 and stx 2). The prototype of enterohemorrhagic E. coli (EHEC) was first described in 1982; it belongs to the serotype O157:H7. In the meantime EHEC of different O-serotypes have been described.

The clinical symptoms which are caused by EHEC range from light to severe gastroenteritis to hemorrhagic colitis which occurs in 10-20 % of all infections. Renal failure (HUS) and death may be caused from infection with EHEC.

Main sources of infection are products from cattle, sheep and goats, especially raw and insufficiently cooked meat, poorly stored meat products, and raw milk.

Using the RIDASCREEN® Verotoxin assay, it is possible to detect this important pathogenicity factor from an enrichment culture. An enrichment of the bacterial culture is required since the toxin content in food can be very low.

   
Format: 96 well microtitreplate
 
Detection limit: Enrichment for 18 hours is sufficient to create a positive result with inoculation of single bacteria.
 
Time requirement: incubation time: 1 h 45 min (regardless of the number of samples) 
 
Sample preparation: Homogenization in medium and overnight incubation
 
Cross reaction: No cross-reactions detected so far beside
the specific detection of SLT-I and SLT-II
 
Samples per kit: up to 46 in duplicate 
 
Positive control: Inactivated verotoxin 1 and 2 
 
Measurement: Microtiter plate reader (450 nm)