Medium Performance
- Easier detection: E. coli O157 is detected by a characteristic mauve colour after only 18 h of incubation, while most other E. coli are blue.
-
Higher specificity of CHROMagar™ E.coli O157 compared to SMAC:
The conventional medium for the detection of E. coli O157 is Sorbitol
MacConkey (SMAC) Agar, which has very poor specificity, thus exhibiting
an abundance of false positives (Proteus, E. hermanii, etc.). Sorbitol
Mac Conkey is also difficult to read because there is a change of
colouration in the case of prolonged incubation.
High Sensitivity: E. coli O157 → 89 %*
*Sensitivity from scientific study: K.A. Bettelheim, 1998. Reliability of CHROMagar O157 for the detection of enterohaemorrhagic E. coli (EHEC) O157 but not EHEC belonging to other serogroups. J.Appl.Microbiol.85:425-428.
Medium Description
Gain flexibility using powder rather than ready to use plates:
Use the entire pack, or, just a portion if there is a need for a smaller number of plates. If kept under appropriate storage temperature, CHROMagar
TM E.coli O157 has a more than 18 months shelf life. This flexibility is essential to avoid the waste resulting from expired-unused plates.
-Referenced in the Chinese Standard for microbiological examination of
food hygiene
GB/T 4789.36-2008.
-
USDA SOP No.: MDP-QA-03 (Page 1 of 6 Title: Quality Assurance (QA)
Controls Revision: 06 Replaces: 04/01/09 Effective: 09/25/09, United
States Department of Agriculture,Agricultural Marketing Service,
Science & Technology, Microbiological Data Program)
Please refer to our notice and Material Safety data sheet for complete information about the medium.
CHROMagar™, Rambach™, AquaCHROM™ are trademarks created by Dr. A. Rambach.
Last Update: 21-May-2019
Focus on E. coli O157
Escherichia coli (E. coli) are bacteria commonly found in the gut of humans and warm-blooded animals. Most strains of E. coli are harmless. Some strains, however, such as Verocytotoxigenic E. coli (VTEC), also known as Shigatoxigenic E. coli (STEC) can cause severe foodborne diseases. Enterohaemorrhagic E. coli (EHEC) are a subset of VTEC, which can cause severe disease in humans such as Haemolytic Uraemic Syndrome (HUS). VTEC have been isolated from the gut contents of many animals, including cattle and sheep. VTEC are mainly transmitted to humans primarily through consumption of contaminated foods, but can also be transmitted through handling animals carrying these bacteria.
E. coli O157 Epidemiologic Issues
The E. coli serotype O157:H7 or its non-motile variant O157:H- is the most common VTEC serotype in relation to public health.
Its significance was recognized in 1982, following two outbreaks in the USA. Since then, more than 180 outbreaks have been reported worldwide, with an estimated W.H.O figure of 70,000 infections per year.
As typical VTEC, E. coli O157 are naturally found in the intestinal contents of livestock, especially cattle and sheep. Their presence in these animals’ faeces makes them an important source of food and water contamination.
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