Escherichia coli O157:H7 Culture, Stool (Sendout)

single page view

General Information

Lab Name
Lab Code
1165
External Test Id
E157C
Description

Useful For:

  • Determining whether Escherichia coli O157:H7 may be the cause of diarrhea
  • Reflexive testing for Shiga toxin and/or E coli O157:H7 nucleic acid amplification test-positive feces
  • This test is generally not useful for patients hospitalized more than 3 days because the yield from specimens from these patients is very low, as is the likelihood of identifying a pathogen that has not been detected previously.

Test Highlights: This test provides evidence of the presence of the bacterium, Escherichia coli O157:H7, in feces in a viable state, and provides an isolate for submission to a health department if needed. Minnesota healthcare professionals are required to report all confirmed or suspected cases of E coli O157:H7 and other Shiga toxin-producing E coli to the Minnesota Department of Health. Mayo Clinic Laboratories clients should refer to their local health departments regarding public health submission of E coli O157:H7 and other Shiga toxin-producing E coli isolates.

Test Algorithm: For positive orders, reflex testing may be performed at additional charge.

Patient Preparation: Patient should avoid use of barium or bismuth for 7 to 10 days prior to specimen collection.

Ordering Requirements:

  • Pre-approved for The Vancouver Clinic (TVC) only. Orders from all other locations require approval from the Laboratory Medicine Resident (LMR) on-call. The recommended test for UW Medicine patients is Enteric Pathogen Panel [STOEPM].
References
Synonyms
E coli, E. coli, E157C, T058
Components

Interpretation

Guidelines
Method

Conventional Culture

Reference Range
Ref. Range Notes
Reference Value: No growth of Escherichia coli O157:H7

Interpretation: The growth of Escherichia coli O157:H7 identifies a potential cause of diarrhea.

Interferences and Limitations

Cautions:

The yield of Escherichia coli O157:H7 is reduced when specimens are delayed in transit to the laboratory (>2 hours from collection for unpreserved specimens).

Check local public health requirements, which may require submission of isolates to a public health laboratory.

Primary testing for Shiga toxin-producing E coli using Shiga toxin polymerase chain reaction and not specifically just for E coli O157:H7 is recommended because roughly half of Shiga toxin-producing E coli are not O157:H7.

Susceptibilities should not be performed on E coli O157:H7 since antibiotics are not used for treatment. Any healthcare professional contemplating a request for susceptibility testing on E coli O157:H7 should consult with the Laboratory Section Director for guidance.

References

Ordering & Collection

Specimen Type
Stool
Collection

Acceptable Collection Containers:

  • Mayo Culture and Sensitivity Stool Transport Vial (T058)
  • Commercially available transport system specific for recovery of enteric pathogens from fecal specimens with 15 mL of non-nutritive transport medium containing phenol red as a pH indicator, either Cary-Blair or Para-Pak Culture and Sensitivity Media

Collection Instructions:

  1. Collect fresh stool and submit 1 gram or 5 mL in container with transport medium (see acceptable containers above).
  2. Place stool in preservative within 2 hours of collection.
  3. Place vial in a sealed plastic bag and transport to the lab.

Reject Due To: Unpreserved feces, ECOFIX preservative, Formalin or PVA fixative.

Approval Required
Pre-approved for The Vancouver Clinic (TVC) only. Orders from all other locations require approval from the Laboratory Medicine Resident (LMR) on-call.
Handling Instructions

Vancouver Clinic (TVC):

  • Store and transport preserved stool at ambient temperature.
  • Expedite transport to the lab. Samples must arrive at Mayo Clinic Labs within 96 hours of collection.

Stability: Ambient (preferred): 4 days; Refrigerated: 4 days; Frozen: Unacceptable.

Quantity
Requested: 1 gram or 5 mL stool in preservative
Minimum: 1 mL stool in preservative

Processing

Receiving Instructions

Fresh stool must be transferred to appropriate preservative within 2 hours of collection. Store and transport preserved stool specimens at ambient temperature.

Login: SPMSND-;AMBIENT STOOL

  • MSNDTO: MAYO
  • MSPTYP: STL
  • MTSTRQ: ;E. coli O157.H7 Culture, Stool (Mayo Test E157C)

Sendouts:

  • Order Mayo Test: E157C

Stability: Ambient (preferred): 4 days; Refrigerated: 4 days; Frozen: Unacceptable.

Reject Due To: Unpreserved feces, ECOFIX preservative, Formalin or PVA fixative.

Misc Sendout

Performance

Lab Department
Frequency
Performed: Monday through Friday. Reported: 2-4 days from sample receipt at Mayo Clinic Labs.
Available STAT?
No
Performing Location(s)
Sendout Mayo Clinic Laboratories
800-533-1710

200 First Street Southwest
Rochester, MN 55901

Billing & Coding

Billing Comments

CPT: 87046-Escherichia coli O157:H7 Culture, Stool-with isolation and preliminary examination

Potential Reflex CPTs, if appropriate:

  • 87077-Bacteria Identification
  • 87153-Aerobe Ident by Sequencing
  • 87077-Additional Identification Procedure
  • 87147-Serologic Agglut Method 2 Ident
  • 87077-Ident by MALDI-TOF mass spec