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Stool *Escherichia coli* O157:H7 DNA Detection by Probe-Based Assay

Published: August 9, 2026Updated: August 16, 2026

This test checks for the presence of *Escherichia coli* O157:H7 bacteria in your stool. This specific strain is linked to severe foodborne illnesses, including bloody diarrhea and kidney failure in some cases.

Quick summary

["A positive result may indicate exposure to this harmful bacteria, prompting further medical evaluation."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
70018-7
Short code
S haemolyticus DNA Bld Ql NAA+probe
Synonyms
S haemolyticus DNA Bld Ql NAA+probe
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
probe-amp-tar
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you’ve experienced symptoms like severe stomach cramps, bloody diarrhea, or vomiting within the past few days. It’s also used in outbreaks or if you’ve been exposed to contaminated food or water.

What to Expect Before the Test

No special preparation is needed, but you may be asked to collect a fresh stool sample in a provided container. Avoid using toilet paper or cleaning products that could alter the sample.

What the Test Results Mean

A positive result confirms the presence of *E. coli* O157:H7 in your stool. This requires immediate medical attention, as treatment may include antibiotics, fluids, and monitoring for complications. A negative result means the bacteria were not detected in this sample.

Common Symptoms of Infection

Symptoms may include sudden onset of severe abdominal pain, bloody diarrhea, nausea, vomiting, or fever. Symptoms can start 3–8 days after exposure but may be delayed in some cases.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

E. coli O157:H7 Stool Test

Frequently asked questions

How long does it take to get results from this test?
Results are typically available within 24 to 48 hours, depending on lab processing times. Your healthcare provider will contact you once the results are ready.
Can I eat or drink before giving the stool sample?
Yes, you can eat and drink normally before providing the sample. Avoid using any cleaning agents or toilet paper that might alter the sample.
What should I do if I have symptoms after the test?
If you develop symptoms like severe diarrhea, blood in stool, or fever after testing, seek medical attention immediately. This test is designed to detect the bacteria, but symptoms may not appear until after the test is completed.
  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 16, 2026. · Read our editorial policy