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UW Health SMPH
American Family Children's Hospital

UW Hospital and Clinics Lab Test Directory

Test Name: Escherichia coli (Shiga) Toxin

Test Code(s): STEC / HCSTEC or as part of Stool Culture Order Panel (HCSTOCEC)

CPT Code(s): 87427

Methodology: Enzyme Immunoassay

Clinical Significance: Qualitative detection of Shiga toxins present in fecal specimens. Should be used as an aid in diagnosis of enterohemorrhagic E. coli infections. Routine ordering with Stool Culture is highly recommended.

Days Performed: Mon, Wed, and Fri.

Turnaround Time: Stat: Not available stat.
Routine: Up to 3 days.


Specimen Requirements

Specimen: Stool

Collection Instructions: Pass stool into a clean, dry bedpan. Do not use toilet paper to collect stool. It may be impregnated with barium salts which may be inhibitory. Transfer stool to Para-Pak Culture & Sensitivity (C&S) kit (orange cap) or sterile screw cap container.

Collection Container: Preferred: Para-PakŪ Culture & Sensitivity (C & S) kit (orange cap)
Also Acceptable: Sterile screw cap container

Collection Volume: Preferred: 1 mL
Pediatrics: 1 mL

Sample Analyzed: Stool

Volume Required: Preferred: 0.3 mL
Pediatrics: 0.3 mL

Specimen Transport: Transport specimen to UWHC Microbiology (B4/231) within 2 hours of collection. Refrigerate sample if transport time will exceed 2 hours.

Unacceptable Criteria: Unrefrigerated fresh stool greater than 2 hours old, unrefrigerated preserved stool specimens greater than 2 hours old, and stool collected into O&P Para-pakŪ containers (pink and gray caps) are not acceptable. Specimens on patients hospitalized more than 3 days are not accepted.

LIMIT: One specimen every 24 hours.

Stability: Ambient: Preserved: 2 hours / Unpreserved: 2 hours
Refrigerated: Preserved: 7 days / Unpreserved: 48 hours
Frozen: Preserved: 7 days / Unpreserved: 48 hours


Interpretation

Expected Results:

Negative

Test Limitations:

Toxin level may be below the detection level of the test. Correlation between the amount of toxin in a sample and clinical presentation has not been established.

Additional Information:

Results should be interpreted by the clinician in conjunction with clinical findings and/or other laboratory results. Optimal results are obtained from specimens tested as soon after collection as possible.

 

Minimal degradation of toxins occurs in specimens that have been refrigerated for up to 48 hours or frozen at -20 degrees Celsius or lower immediately after collection.

 

 

For an Indeterminate result, another specimen should be obtained and retested.

 

Positive results are called to a health care provider.

 

Because these agents do not cause hospital acquired infection, specimens on patients who have been hospitalized greater than 3 days will require approval of the Director of Microbiology or Pathology Resident.

stool culture enteric e coli e. coli

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