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HelpTest Code STFRP Shiga Toxin, Molecular Detection, PCR, Feces
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Reporting Name
Shiga Toxin PCR, FSpecimen Type
FecalAdditional Testing Requirements
In some cases, there may be local public health requirements that impact Mayo Clinic Laboratories (MCL) clients and require additional testing on specimens with positive results for this test. MCL recommends that clients retain an aliquot of each specimen submitted for testing to perform such additional testing, if needed. Alternatively (not preferred), clients who want their specimen returned from MCL should call MCL as soon as possible, at the latest within 96 hours of specimen collection, to request that MCL return an aliquot of the submitted specimen to them. Clients will be responsible for submitting their specimens to appropriate public health departments.
Necessary Information
Specimen source is required.
Specimen Required
The high sensitivity of amplification by polymerase chain reaction requires the specimen to be processed in an environment in which contamination of the specimen by shiga toxin DNA is unlikely.
Submit only 1 of the following specimens:
Preferred:
Specimen Type: Preserved feces
Supplies: Culture and Sensitivity Stool Transport Vial (T058)
Container/Tube: Commercially available transport system specific for recovery of enteric pathogens from fecal specimens (15 mL of nonnutritive transport medium containing phenol red as a pH indicator, either Cary-Blair or Para-Pak C and S)
Specimen Volume: Representative portion of feces; 5 mL
Collection Instructions:
1. Collect fresh fecal specimen and submit in container with transport medium.
2. Place feces in preservative within 2 hours of collection.
Specimen Stability Information: Ambient (preferred) <7 days/Refrigerated <7 days
Acceptable:
Specimen Type: Unpreserved feces
Supplies:
-Stool container, Small (Random), 4 oz Random (T288)
-Stool Collection Kit, Random (T635)
Container/Tube: Fecal container
Specimen Volume: Representative portion of feces
Collection Instructions: Collect fresh fecal specimen and submit representative sample in fecal container.
Specimen Stability Information: Refrigerated (preferred) <7 days/Frozen <7 days
Reject Due To
| Formed feces or feces in gel transport medium EcoFix preservative; formalin or PVA fixative Preserved feces received frozen |
Reject |
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Fecal | Varies | 7 days |
Specimen Minimum Volume
1 mL
Special Instructions
Day(s) Performed
Monday through Sunday
Specimen Retention Time
7 daysReport Available
1 to 2 daysReference Values
Not applicable
Useful For
Sensitive, specific, and rapid detection of the presence of Shiga toxin-producing organisms such as Escherichia coli O157:H7 and Shigella dysenteriae type 1 in stool
This test is not recommended as a test of cure.
Testing Algorithm
For more information see Laboratory Testing for Infectious Causes of Diarrhea.
CPT Code Information
87798
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| STFRP | Shiga Toxin PCR, F | 80679-4 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| SRC59 | Specimen Source | 31208-2 |
| 56052 | Result | 80679-4 |
Supportive Data
This assay was prospectively clinically validated using 204 stool specimens submitted for the antigen test (enzyme immunoassay: EIA method). In addition, the assay was used to test 85 archived fecal specimens previously tested for either Escherichia coli O157:H7 or Shiga toxin by EIA, with results compared to the prior results. Discordant results on the archived specimens were resolved by submission to the Minnesota Department of Health (MDH) for polymerase chain reaction (PCR) using different primers. Compared to a combined gold standard (ie, positive by EIA, culture, or MDH PCR) the Mayo PCR assay had 100% sensitivity and specificity; in total, 46 positive and 243 negative specimens were evaluated. No cross-reactivity was observed when tested on a panel of more than 50 organisms commonly found in stool. The analytical sensitivity was 2 targets/mcL.
Forms
If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:
-Microbiology Test Request (T244)
-Gastroenterology and Hepatology Test Request (T728)
-Renal Diagnostics Test Request (T830)
-Coagulation Test Request (T753)