Test Catalog

Test Id : E157C

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Escherichia coli O157:H7 Culture, Feces

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Overview

Test Catalog

Useful For
Suggests clinical disorders or settings where the test may be helpful

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.

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.

Reflex Tests
Lists tests that may or may not be performed, at an additional charge, depending on the result and interpretation of the initial tests.

Test Id Reporting Name Available Separately Always Performed
GID Bacteria Identification No, (Bill Only) No
ISAE Aerobe Ident by Sequencing No, (Bill Only) No
REFID Additional Identification Procedure No, (Bill Only) No
EC Serologic Agglut Method 2 Ident No, (Bill Only) No
RMALD Ident by MALDI-TOF mass spec No, (Bill Only) No

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

When this test is ordered, the reflex tests may be performed at an additional charge.

 

For more information see Laboratory Testing for Infectious Causes of Diarrhea.

Method Name
A short description of the method used to perform the test

Conventional Culture

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.

Yes

Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

E. coli O157:H7 Culture, F

Aliases
Lists additional common names for a test, as an aid in searching

Aerobic Bacterial Stool Culture

Enteric pathogens

E. coli O157:H7 Stool Culture

Escherichia coli O157:H7 Stool Culture

Stool Culture

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

When this test is ordered, the reflex tests may be performed at an additional charge.

 

For more information see Laboratory Testing for Infectious Causes of Diarrhea.

Specimen Type
Describes the specimen type validated for testing

Fecal

Additional Testing Requirements

In some cases, local public health requirements may impact Mayo Clinic Laboratories clients, requiring, for example, submission of isolates to public health laboratories. Clients should familiarize themselves with local requirements and are responsible for submitting isolates to appropriate public health laboratories. Clients can obtain isolates of Escherichia coli O157:H7 species recovered from specimens submitted to Mayo Clinic Laboratories by calling 800-533-1710 as soon as possible after reporting (to ensure viability of the bacterium).

Shipping Instructions

Specimen must arrive within 96 hours of collection.

Necessary Information

Specimen source is required.

ORDER QUESTIONS AND ANSWERS

Question ID Description Answers
Q00M0083 Specimen Source

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Patient Preparation: Patient should not use barium or bismuth for 7 to 10 days before specimen collection.

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 non-nutritive transport medium containing phenol red as a pH indicator, either Cary-Blair or Para-Pak C and S)

Specimen Volume: Representative portion of fecal specimen

Collection Instructions:

1. Collect fresh feces and submit 1 gram or 5 mL in container with transport medium.

2. Place feces in preservative within 2 hours of collection.

3. Place vial in a sealed plastic bag.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.

1 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Unpreserved feces
ECOFIX preservative
Formalin or PVA fixative 		Reject

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Fecal Ambient (preferred) 4 days
Refrigerated 4 days

Useful For
Suggests clinical disorders or settings where the test may be helpful

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.

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

When this test is ordered, the reflex tests may be performed at an additional charge.

 

For more information see Laboratory Testing for Infectious Causes of Diarrhea.

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Diarrhea may be caused by a number of agents, including bacteria, viruses, parasites, and chemicals; these agents may result in similar symptoms. A thorough patient history covering symptoms, severity and duration of illness, age, travel history, food consumption, history of recent antibiotic use, and illnesses in the family or other contacts will help the healthcare professional determine the appropriate testing to be performed.

 

Shiga toxin-producing Escherichia coli (STEC) are E coli strains capable of producing Shiga toxin, which can result in diarrhea that can be bloody. The incubation period between exposure and symptom onset is 1 to 9 days. Hemolytic-uremic syndrome (HUS) is a systemic complication of STEC infection and is characterized by kidney failure, microangiopathic hemolytic anemia, and nonimmune thrombocytopenia. HUS complicates approximately 15% of STEC infections in children younger than 10 years and 6% to 9% overall.

 

Treatment of STEC infection consists of supportive care. Antibiotic therapy is generally not beneficial in patients with STEC infection and has been associated with development of HUS in some studies. Thus, when STEC is clinically suspected, antibiotics should be withheld. Antiperistaltic agents also increase the risk of systemic complications and should be avoided.

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

No growth of Escherichia coli O157:H7

Interpretation
Provides information to assist in interpretation of the test results

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

Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

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.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. DuPont HL. Persistent diarrhea: A clinical review. JAMA. 2016;315(24):2712-2723. doi:10.1001/jama.2016.7833

2. Page AV, Liles WC. Enterohemorrhagic Escherichia coli infections and the hemolytic-uremic syndrome. Med Clin North Am. 2013;97(4):681-695

3. Nelson JM, Griffin PM, Jones TF, et al. Antimicrobial and antimotility agent use in persons with shiga toxin-producing Escherichia coli O157 infection in FoodNet Sites. Clin Infect Dis. 2011;52(9):1130-1130

Method Description
Describes how the test is performed and provides a method-specific reference

The fecal specimen is inoculated onto sorbitol MacConkey agar. After incubation, suspect colonies are identified using one or a combination of the following techniques: matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, conventional biochemical tests, carbon source utilization, serologic methods, or nucleic acid sequencing of the 16S ribosomal RNA gene. Isolates are reported as Escherichia coli O157:H7 or Escherichia coli O157, unable to detect H7 antigen.(Pillai DR, Griener T. Culture for Campylobacter and related organisms. In: Leber AL, Church DL, eds. Clinical Microbiology Procedures Handbook. 4th ed. ASM Press; 2016:Section 3.8.2)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information

No

Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Friday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

2 to 4 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

7 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test

Rochester

Fees
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their account representative. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.

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

87077-Bacteria Identification (if appropriate)

87153-Aerobe Ident by Sequencing (if appropriate)

87077-Additional Identification Procedure (if appropriate)

87147-Serologic Agglut Method 2 Ident (if appropriate)

87077-Ident by MALDI-TOF mass spec (if appropriate)

LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
E157C E. coli O157:H7 Culture, F 10851-4
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
E157C E. coli O157:H7 Culture, F 10851-4

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports