Safepath Laboratories

SafePath E. coli 0157 Immunoassay Kit 960-well
Product Code: ECM-960

Intended Use

The SafePath E. coli 0157 assay is an enzyme-linked immunosorbent assay
(ELISA) that may be used to screen meat products for the presence of E. coli
0157 antigen.


Strains of Escherichia coli that produce Shiga-like toxins (SLTs), also known as
Verocytotoxins (VTs), are an important cause of human disease. Clinical
manifestations of infection include diarrhea, hemorrhagic colitis (HC) and
hemolytic uremic syndrome (HUS). Although Shiga-like toxin producing E. coli
(SLTEC) belong to many O serogroups, serotypes 0157:H7 and 0157:H are the
predominant SLTEC associated with HC and HUS. Outbreaks of HC and HUS due to
E. coli 0157 have been linked to consumption of undercooked ground beef. Prevalence
studies indicate that up to 3.7% of retail meats may contain E. coli 0157. Although this
may seem low compared to some other foodborne pathogens, the seriousness of
disease caused by E. coli 0157 has made this pathogen a major food safety concern.

Detection of E. coli 0157:H7 in meats by cultural methods is time consuming,
requiring several days to obtain presumptive positive results. Typically, meat
samples are cultured in primary enrichment broth which is plated onto sorbitol
-MacConkey (SMAC) agar. Non-sorbitol fermenting colonies are then
subcultured for identification by serotyping or related methods. As some E. coli
0157 strains associated with HC and HUS ferment sorbitol,
this approach may give false negative results.

The SafePath E. coli 0157 ELISA is a rapid and reliable test which
significantly reduces the time required to screen meats for the presence of E.
coli 0157. Primary enrichment cultures grown for 8-16 hours can be tested in
less than one hour, allowing ELISA-negative product to be released within 24
hours. Enrichment broths presumptively positive for E. coli 0157 on the basis of
positive ELISA tests can be cultured further for confirmation by standard

Principle of the Test

The SafePath E. coli 0157 ELISA is a double antibody (sandwich) ELISA
utilizing specific anti-E. coli 0157 antibodies coated to microwells. After
addition of the sample and the enzyme conjugate, a positive reaction
(indicating the presence of E. coli 0157 antigen) produces a deep blue color.
Addition of the Stop Solution ends the assay and turns the blue color to yellow.
The results may be read visually or with an ELISA reader.

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