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HelpTest Code STFRP Shiga Toxin, Molecular Detection, PCR, Feces
Reporting Name
Shiga Toxin PCR, FPerforming Laboratory
Mayo Clinic Laboratories in Rochester
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.
Method Name
Real-Time Polymerase Chain Reaction (PCR) using Fluorescent Resonance Energy Transfer (FRET)
Additional 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
Specimen Type
FecalSpecimen Minimum Volume
1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Fecal | Varies | 7 days |
Reject Due To
| Formed feces or feces in gel transport medium EcoFix preservative; formalin or PVA fixative Preserved feces received frozen |
Reject |
Reference Values
Not applicable
Interpretation
A positive polymerase chain reaction (PCR) result indicates the likely presence of Shiga toxin-producing Escherichia coli in the specimen. Although Shigella dysenteriae serotype 1 may produce a positive result, it is extremely rare in the United States.
A negative result indicates the absence of detectable Shiga toxin DNA in the specimen, but does not rule out the presence of Shiga toxin-producing E coli and may occur due to inhibition of PCR, sequence variability underlying primers or probes, or the presence of Shiga toxin DNA in quantities less than the limit of detection of the assay. Shiga toxins are encoded on mobile genetic elements and can theoretically be lost by their bacterial host.
Day(s) Performed
Monday through Sunday
Report Available
1 to 2 daysTest Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.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 |
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)
Testing Algorithm
For more information see Laboratory Testing for Infectious Causes of Diarrhea.