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Test ID: Shiga toxin/E coli O:157 Toxin Assay
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Shiga toxin assay
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Test for the detection of the presence of Shiga toxins in stool specimens
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Useful For
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Diagnosis of Shiga-toxin producing E coli gastrointestinal infections
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Method name and description
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Commercially available enzyme immunoassay for the detection of Shiga toxins I and II (Verotoxins).
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Clinical information
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The symptoms of Shiga-toxin porducing E.coli (STEC) infections vary for each person but often include severe stomach cramps, diarrhea (often bloody), and vomiting. If there is fever, it usually is not very high (less than 101˚F/less than 38.5˚C). Most people get better within 5–7 days.
Some infections are very mild, but others are severe or even life-threatening. Around 5–10% of those who are diagnosed with STEC infection develop a potentially life-threatening complication known as hemolytic uremic syndrome (HUS). Clues that a person is developing HUS include decreased frequency of urination, feeling very tired, and losing pink color in cheeks and inside the lower eyelids. Persons with HUS should be hospitalized because their kidneys may stop working and they may develop other serious problems. Most persons with HUS recover within a few weeks, but some suffer permanent damage or die.
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Aliases
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- E coli O:157
- Shiga Toxin
- Shiga toxin / EC O157
- Shiga toxin I and II
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Specimen type / Specimen volume / Specimen container
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Specimen type
Note: Bloody or liquid stools collected within 6 days of onset from patients with abdominal cramps have the highest yield.
Specimen volume
- 1-2 g or ml (for liquid stool)
Specimen container
- Sterile leak proof container
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Collection instructions / Special Precautions / Timing of collection
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Collection instructions
Adults and older children:
- Wash hands before collection. Put on gloves if necessary.
- Urinate before collecting stool.
- Collect specimen in a clean bed pan or use plastic wrap placed between the toilet seat and the bowl ( to prevent feces falling into toilet water).
- Collect the stool into the labelled container using the spoon provided with container or any disposable spoons (Sample areas of the specimen which appear bloody, slimy or watery).
- Close the lid tightly and place in biohazard bags provided.
- Flush the remaining stool down the toilet and dispose the plastic wrap or pan.
- Wash hands after collection.
Infants and Toddlers
- Infants - Take the stool out of the diaper. If your child has loose or runny stools, put the plastic side of the diaper next to the skin long enough to collect stool from it.
- Toddlers - If your toddler is toilet trained, you can use a clean, dry training potty, training pants, or a diaper to collect the stool.
Timing of collection
- The ideal specimen for testing is diarrheal stool; stool specimens should be collected as soon as possible after diarrhea begins, while the patient is acutely ill
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Relevant clinical information to be provided
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- Patient clinical condition
- Antibiotics given
- Suspected HUS
- Duration of illness
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Storage and transport instructions
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- ≤2 hrs. at room temperature o
- If delay, then refrigerate at 2-8°C and send to the laboratory within 24 hrs of collection
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Specimen Rejection Criteria
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- Unlabelled and Mislabeled Sample
- No relevant clinical details provided with the request. (Please note that where applicable, the relevant clinical details should reflect those on the patient’s electronic record at the time the order was placed).
- Improper container
- Leaking specimen
- Duplicate samples within 72 hours
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Biological reference intervals and clinical decision values
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Negative result
Shiga Toxin (I/II) - Negative
Positive result
Shiga Toxin (I/II) – Positive
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Factors affecting test performance and result interpretation
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- Improper technique
- Improper collection
- Improper storage
- Improper container
- Prior Antibiotic consumption
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Turnaround time / Days and times test performed / Specimen retention time
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Turnaround time
Days and times test performed:
- Specimens accepted on all days. Test performed once a week in the HGH microbiology laboratory. Specimens received in other microbiology laboratories will be sent to the .HGH microbiology laboratory for testing
Specimen retention time:
- 48 hrs. after final report
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