Escherichia coli O157:H7 Culture, Stool (Sendout)

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

Mayo Clinical & Interpretive Information: Escherichia coli O157:H7 Culture, Feces

Synonyms

E coli, E. coli, E157C, T058

Interpretation

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.

Guidelines

Washington DOH Notifiable Conditions

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:

Collect fresh stool and submit 1 gram or 5 mL in container with transport medium (see acceptable containers above).
Place stool in preservative within 2 hours of collection.
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

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