Oxoid - Product Detail

Introduction
Certain strains of Escherichia coli have been implicated in cases of haemorrhagic colitis (HC) and haemolytic ureamic syndrome (HUS).
It has been shown that these strains produce a vero-cytotoxin (VT). The Escherichia coli serotype most frequently isolated from HC and HUS case is O157:H7. Isolation of this serotype from a diarrhoeal stool particularly with the presence of blood is indicative of a vero-cytotoxin producing strain.
The Oxoid Escherichia coli O157 Latex Test will demonstrate by slide agglutination Escherichia coli strains possessing the O157 serogroup antigen. The test is best used in conjunction with Sorbitol MacConkey Agar CM813. E.coli O157:H7 strains do not ferment Sorbitol and therefore give colourless colonies on this medium. The majority of Escherichia coli isolates do ferment sorbitol and give characteristic pink colonies.
Sorbitol MacConkey Agar CM0813 should be used as the primary screen. Non-Sorbitol fermenting colonies can then be tested with the latex reagents, to determine whether the isolate belongs to the O157 serogroup and therefore a potential VT-producing strain.

Components of the kit
DR0621 Test Latex
Consists of blue latex particles sensitised with specific rabbit antibody reactive with the O157 somatic antigen. Each kit contains sufficient reagent for 100 tests.
DR0622 Control Latex
Consists of blue latex particles sensitised with pre-immune rabbit globulin. Each kit contains sufficient reagent for 100 tests.
DR0623 Positive Control Suspension
A suspension of inactivated Escherichia coli O157 cells in buffer. Sufficient for 25 tests.
DR0624 Negative Control Suspension
A suspension of Escherichia coli O116 cells in buffer. Sufficient for 25 tests.
DR0500 Reaction Cards
There are 35 disposable reaction cards provided in the kit.
Instruction leaflet.

Materials required but not provided
Microbiological loop and bunsen burner.
0.85% saline.
Suitable disinfectant e.g. sodium hypochlorite solution >1.3% W/W.

For full procedure please see product insert.

Storage
This kit should be stored at 2-8^oC. Do not freeze. Do not use after the expiry date printed on the outside of the carton.

Precautions
Reagents contain 0.1% sodium azide as a preservative.
Sodium azide may react with lead or copper plumbing to produce metal azides which are explosive by contact detonation. To prevent azide accumulation in plumbing, flush with copious amounts of water immediately after waste disposal.

References
1. Borczyk A., Lior H., Crebin B (1987) Int. J Food. Microbial. 4, 347-349.
2. Konowalchuk, J., Speirs, J. and Stavric S. (1977) Infect. Immun 18, 775-779.
3. Scotland S., Day N and Rowe B. (1980) FEMS. Microbiol. Lett, 7, 15-17.
4. Centres for Disease Control (1982) Morbid Mortal Wkly 31 580-585
5. Karmali M., Still, B., Petrick M., and Lim C. (1983), Lancet I, 619-620.
6. Johnson, W., Liroh, H., and Bezanson, (1983) Lancet I, 76.
7. March S., and Ratnam (1986) J. Clin. Microbiol. 23, - 869-872.
8. Krishnan, C., Fitzgerald V., Dakin S., and Behme R. (1987) J. Clin. Microbial. 25, 1043-1047.
9. P.A. Chapman (1989) Evaluation of Commercial latex slide test for identifying Escherichia coli O157.42:1109-1110.