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: Escherichia coli O157 DNA Qualitative by Probe in Stool

Published: August 9, 2026Updated: August 17, 2026

: This test looks for the DNA of Shiga toxin-producing Escherichia coli O157 in a stool sample using a nucleic acid probe method, helping identify this specific bacteria when someone has diarrhea.

Quick summary

[": A positive result indicates that DNA from E. coli O157 was detected in the stool, suggesting infection with this bacterium."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
97320-6
Short code
E coli O157 DNA Stl Ql NAA+probe
Synonyms
E coli O157 DNA Stl Ql NAA+probe
Category
chemistry
Sample
stool
Container
Clean container
Units
N/A
Ref low
10
Ref high
40
Critical range
— – 500 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
probe-amp-tar
CPT
84484
SNOMED
302774002
Specimen volume
5 g
Stability
Refrigerated: 24h, Frozen: 7d
TAT
4–24 hours
Order
routine

: What the Test Measures

: The test detects genetic material (DNA) belonging to Escherichia coli O157, a type of bacteria that can cause bloody diarrhea and, in some people, serious complications. The probe method identifies bacterial DNA directly, which can provide results relatively quickly compared with traditional culture.

: Why It Is Ordered

: A healthcare provider may order this test when a person has diarrhea, especially bloody diarrhea, stomach cramps, or a recent history of eating undercooked meat, unpasteurized products, or contaminated food or water. It is used to confirm whether E. coli O157 is the cause of illness.

: How the Sample Is Collected

: A stool specimen is collected in a clean container according to the instructions provided by the laboratory or healthcare team. The sample is then sent to the lab, where it is processed to detect E. coli O157 DNA.

: Understanding the Results

: A detected (positive) result means E. coli O157 DNA was found in the stool, supporting infection with this organism. A not-detected (negative) result means the DNA was not found, though testing can occasionally miss low levels of bacteria. Your provider will interpret results together with symptoms and other tests.

Reference range

Adult: 10-40 U/LN/A

Specimen: stool

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

: E. coli O157 is a Shiga toxin-producing bacterium associated with foodborne illness and outbreaks. Prompt detection supports appropriate management and helps prevent the spread of infection, and it also helps identify people at risk of complications such as hemolytic uremic syndrome, which requires close medical follow-up.

Short name

: E. coli O157 PCR

Frequently asked questions

: Is this the same as a stool culture for E. coli O157?
: No. A stool culture grows the bacteria in the lab, while this test detects bacterial DNA directly. Both can identify E. coli O157, but they use different methods and may be used together or separately depending on the situation.
: Does a positive result always mean severe illness?
: Not necessarily. Some people have mild or no symptoms, while others develop severe diarrhea or complications. A positive result should always be discussed with your healthcare provider, who will assess your symptoms and overall health.
: How can I reduce the risk of spreading E. coli O157?
: Good handwashing, especially after using the bathroom or handling food, and careful cooking of meats, along with avoiding unpasteurized products and contaminated water, can lower the risk of infection and spread to others.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy