E. coli O157 and Non-O157 Shiga Toxin Producing E. coli (STEC) – Enteric Culture

Testing Indications

Note to Submitters

Enteric culture is performed at the request of public health units for case management and outbreak investigations. Specimens are accepted only from health units.

If you are a clinician, please use a community laboratory to perform your testing. If you suspect an outbreak contact your local Health Unit.

Screening for non-O157 shiga toxin producing E. coli (STEC) is performed by qPCR. The Public Health Ontario laboratory will test for non-O157 STEC on request from a patient who

  • presents with acute bloody diarrhea or has hemolytic uremic syndrome (HUS) AND
  • is negative for other enteric pathogens including E. coli O157

Specimen Collection and Handling

Specimen Requirements

Test Requested Required Requisition(s) Specimen Type Minimum Volume Collection Kit

E. coli O157 culture1


2.0 ml2,3

Cary Blair

Available in either PHO Cary Blair Kit – Kit Order #390049 or Enteric Bacteriology kit #390036


Submission and Collection Notes


Enter the name of the organism if you are suspecting a specific organism, e.g. E. coli O157 or non-O157 shiga toxin producing E. coli (STEC)


Collect a minimum of 2. 0 ml of liquid faeces or add faeces up to the fill line indicated. DO NOT overfill.


Follow the instructions found in the Faeces Enteric Bacteriology Kit or Enteric Outbreak Kit


The stool specimen must be received in the laboratory and processed within 5 days of collection. Specimens received after 5 days of collection will not be tested. Only one sample per patient is tested per collection date.

Preparation Prior to Transport

Label the specimen container with the patient’s full name, date of collection and one other unique identifier such as the patient’s date of birth or Health Card Number. Failure to provide this information may result in rejection or testing delay. 

Special Instructions

Specimens should be stored at 2-8°C following collection and shipped to PHO laboratory on ice packs.

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

E. coli O157 enteric culture testing is performed Monday to Friday.

Screening for non-O157 shiga toxin producing E. coli (STEC) by qPCR is performed twice a week.

Turnaround time is up to 6 days from receipt at PHO laboratory.


Results are reported to the ordering physician or health care provider as indicated on the requisition.

Specimens that are positive for E. coli O157 and non-O157 shiga toxin producing E. coli (STEC) by qPCR are reported to the Medical Officer of Health as per the Ontario Health Protection and Promotion Act.

Test Methods

Specimens are tested by conventional bacterial culture.

Bacterial identification includes biotyping and serotyping procedures.

Screening for non-O157 shiga toxin producing E. coli (STEC) is performed by qPCR.

Antimicrobial susceptibility testing is not performed on E. coli O157 and non-O157 shiga toxin producing E. coli (STEC).

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Updated 4 Jan 2019