Enteric - Bacterial Culture

Testing Indications

Note to Submitters

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

Enteric – bacterial culture testing for community physicians is available through community or hospital laboratories. If an outbreak is suspected, the local public health unit should be notified and contacted.

Routine stool culture includes Salmonella, Shigella, Campylobacter, pathogenic Yersinia and E. coli O157:H7. Culture for Vibrio is available upon request. Indicate on the test requisition if a specific pathogen is suspected as well as travel or exposure history. 

Screening for non-O157 shiga toxin producing E. coli (STEC) is performed by polymerase chain reaction (PCR) upon request. 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

Aeromonas and Plesiomonas enteric culture from stool should only be performed when a history of travel or consumption of seafood is provided, when specifically requested by the ordering physician or as part of an investigation of an outbreak where standard procedures have failed to find the cause.

Clostridium perfringens enterotoxin (EIA) is routinely performed on all food-borne outbreak investigations.

Limitations

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. 

Storage and 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 PHOL on ice packs.

Test Frequency and Turnaround Time (TAT)

Enteric culture testing is performed Monday to Friday. 

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

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

Specimens are tested by conventional bacterial culture. 
Bacterial identification includes Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectometry (MALDI-TOF), biotyping and serotyping procedures.

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

Antimicrobial susceptibility testing is routinely performed on Shigella, and Vibrio.

Antimicrobial susceptibility testing is routinely performed on Salmonella Typhi and Salmonella Paratyphi only and for clinical indications (from blood or sterile sites, infants <1 year old, immuno-compromised patients and hospitalized patients – if documented).

Antimicrobial susceptibility testing is performed on Campylobacter and Yersinia upon request only or for clinical indications (from blood or sterile sites, infants <1 year old, immune-compromised patients and hospitalized patients – if documented).

Antimicrobial susceptibility testing on other bacteria is available upon request.

Reporting

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

Specimens that are positive for Salmonella, Shigella, Campylobacter, pathogenic Yersinia, E. coli O157:H7 and non-O157 shiga toxin producing E. coli (STEC) and Vibrio cholerae are reported to the Medical Officer of Health as per the Ontario Health Protection and Promotion Act.