| Method | ISO 16654 | FDA BAM Chapter 4A | FSIS MLG 5.05 |
|---|---|---|---|
| Pre-enrichment | mTSB+N, 41.5 ± 1°C; 6 and 18 -24 h |
mBPWp, 37 ± 1°C; 5 h |
mBPWp, 37 ± 1°C; 5 h |
| Selective enrichment | Immunomagnetic Concentration |
Add ACV supplement, 42 ± 1°C; 18-24 h optional immunomagnetic separation |
Immuno- magnetic separation |
| Isolation | CT-SMAC agar, 37°C; 18-24 h |
CT-SMAC Agar + chromogenic agar (Rainbow O157 Agar or R&F E.coli O157 Agar), 37 ± 1°C; 18-24 h |
Rainbow O157 Agar, 35 ± 2°C; 24-26h |
E. coli O157/EHEC/STEC/VTEC Testing
Rapid Testing Solutions for the
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Amongst the pathogenic Escherichia coli, verotoxin-forming strains (STEC or VTEC) have gained importance in recent years - and in particular the group of enterohaemorrhagic E. coli (EHEC) with its highly pathogenic serovar O157:H7 strain. The main sources of infection are contaminated, raw or insufficiently heated foods of animal origin, such as meat and dairy products. EHEC is capable of inducing life threatening illnesses, particularly in people with immune deficiency, young children and the elderly. Recent years have seen a drastic increase in the incidence of food contamination caused by E. coli O157.
Merck provides a comprehensive selection of products for the enrichment, detection and isolation of verotoxin-forming Escherichia coli strains. These include:
- Granulated Culture Media: Unique and convenient dehydrated media meeting the highest industry performance standards as described in ISO 11133.
- Singlepath® Lateral Flow Tests: Highly innovative immunoassays in the “pregnancy test” format enabling detection with ultimate convenience in as little as 20 minutes after enrichment.
E. coli are Gram-negative, non-sporulating, facultative anaerobic bacilli. They can grow on a wide range of substrates and at temperatures ranging from below 15°C up to 45°C or even higher, as seen with certain laboratory strains (optimum temperature 37°C). Some strains are motile and possess flagella.
Amongst the pathogenic E. coli, Verotoxin-forming strains (STEC or VTEC) have gained importance in recent years. The group of enterohaemorrhagic E. coli (EHEC) with its highly pathogenic serovar O157:H7 strain is particularly interesting in this respect. The main sources of infection are contaminated, raw or insufficiently heated foods of animal origin, such as meat and dairy products. The reservoir for EHEC is the gut of ruminants. The microorganisms can enter food during the processing of meat and dairy products if hygienic conditions are inadequate. The drastic increase in the incidence of food contamination caused by E. coli O157 demands reliable and rapid methods of detection.
EHEC Infection
EHEC is capable of inducing life threatening illnesses, particularly in people with immune deficiency, young children and the elderly. Although the most common cause of EHEC is E. coli O157, other serotypes, such as O26, O45, O103, O111, O121, and O145, are also relatively frequent causes of infection.
Typical symptoms are severe abdominal pain and diarrhea, which is initially watery but often becomes bloody. These are occasionally accompanied by vomiting. The illness is usually self-limited and lasts for an average of 8 days. In up to 10% of all cases, kidney complications (so-called hemolytic-uremic syndrome or HUS) occur, which can lead to temporary or even permanent kidney damage. Neurological symptoms may also occur.
