Escherichia coli (E. coli) is a member of the coliform group of bacteria. Although most strains of E. coli are harmless, others such as E.coli O157:H7 can make you sick. It has been identified as one of the major causative organisms of water and foodborne diseases. E. coli strains are found in the environment, foods, and intestines of people and animals. E. coli testing is used as a measure of water and food quality or level of contamination of surfaces with potentially harmful bacteria.
Handling Samples for E. coli Testing
Proper sample handling is required to maintain the sample integrity during sample collection and between sample collection and analysis. Samples should be collected using sterile containers. Sampling bottles should contain sodium thiosulfate to neutralize chlorine. If surface samples are to be collected, sterile swabs should be used. If the samples will not be processed immediately, they should be refrigerated at a temperature of < 10 degrees Celsius. E. coli samples must not be kept for more than six hours from the time of collection to initiation of analyses. Samples must be processed within 2 hours of arriving to the lab.
E. coli Testing in Water
Water samples are tested for total coliform and E. coli bacteria.
E. coli Testing in Slaughter Establishments
The Canadian Food Inspection Agency (CFIA) has set the sampling frequency for E. coli testing in slaughter establishments. This frequency is determined by production volume. With the exception of Very Low Production Volume establishments, establishments should collect samples at the rate set out in the Table below or at a minimum of at least once a week.
| Slaughter Species | Testing Frequency |
|---|---|
| Cattle, sheep, goats, horses, mules and other equines | 1 test per 300 carcasses. |
| Swine | 1 test per 1,000 carcasses. |
| Chickens | 1 test per 22,000 carcasses |
| Turkeys, ducks, geese and guineas, squabs and ratites | 1 test per 3,000 carcasses |
Coliforms are tested for as indicators of sewage contamination. They can be tested for in water samples, swab samples, and air samples. Water samples, if the water comes from a chlorinated system, must be treated with sodium thiosulfate. Swab samples must use liquid culture swabs to preserve the sampled bacteria. Testing can be done as presence/absence samples or as enumeration. For sampling information, please contact us so that we can discuss the needs of your unique situation.
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