Identification of e. coli o157 by dynabeads® Anti- E. Coli O157

Help on accessing alternative formats, such as Portable Document Format (PDF), Microsoft Word and PowerPoint (PPT) files, can be obtained in the alternate format help section.

Health Protection Branch
Ottawa

Don Warburton
Evaluation Division
Bureau of Microbial Hazards,
Food Directorate, Health Canada
Postal Locator: 2204A1
Ottawa, Ontario, K1A 0L2

1. Application

This method is applicable to the isolation of viable Escherichia coli O157 in foods to determine compliance with the requirements of Sections 4 and 7 of the Food and Drugs Act.

2. Principle

THE Dynabeads^® anti- E. coli O157 test offers a rapid culture technique based on the selective enrichment of E. coli O157 directly from pre-enriched samples using the technology of ImmunoMagnetic Separation (IMS). The basis of IMS is a uniform, superparamagnetic, polystyrene microsphere called Dynabeads®. In this assay, Dynabeads® are coated with absorbed and affinity purified anti -E. coli O157 antibodies. The beads are incubated with 1ml of pre-enriched sample. During this incubation, E. coli O157 present in the sample will bind to the surface of the bead. The bead-bacteria complexes are separated from the sample using a magnetic particle concentrator (Dynal MPC®- M). The bead-bacteria complexes are then plated onto selective culture media . After incubation, the plates are examined for colonies which exhibit characteristics typical for the growth of E. coli O157.

Dynabeads^® and Dynal MPC^® are trademarks of Dynal A.S Oslo, Norway.

3. Definition of terms

See Appendix A of Volume 3.

4. Collection of samples

See Appendix B of Volume 3.

5. Materials and special equipment