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E. coli O157:H7 Antibody Detection (Serum/Plasma) – Immunoassay Probe

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

This test checks for antibodies in your blood that may indicate past exposure to *Escherichia coli* (E. coli) strain O157:H7, a bacterium often linked to foodborne illness or contaminated water.

Quick summary

["A simple blood test to detect immune response to a harmful bacterial strain that can cause severe illness."]

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

Key facts at a glance

LOINC
97319-8
Short code
ETEC DNA Stl Ql NAA+probe
Synonyms
ETEC 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

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you’ve had symptoms like severe diarrhea, bloody stools, or kidney problems (especially in children) that could suggest an E. coli infection. It may also be used in outbreaks, food safety investigations, or if you’ve been exposed to known risk factors (e.g., eating undercooked meat, contaminated produce).

What to Expect Before the Test

No special preparation is needed. You’ll have a small blood sample drawn from your arm. If you’re pregnant, have a bleeding disorder, or are on blood-thinning medication, let your provider know before the test.

What the Test Results Mean

Positive results suggest your immune system has recognized E. coli O157:H7, but they don’t confirm an active infection. Antibodies may appear weeks after exposure. Negative results mean no detectable antibodies were found at this time.

Possible Outcomes and Next Steps

If positive: Follow your doctor’s advice for monitoring or treatment. If negative: Symptoms may still be from another cause. Your provider may recommend stool testing or other diagnostics if symptoms persist.

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.

Clinical Significance: What This Test Indicates

Short name

E. coli O157:H7 Antibody Screen

Frequently asked questions

Does this test diagnose an active E. coli infection?
No. This test detects antibodies (immune proteins) produced after exposure, not live bacteria. For active infection, stool tests or culture are needed. Antibody tests are often used retrospectively or in outbreaks.
Can I get this test if I’ve already had E. coli?
Yes, this test can confirm past exposure if your body produced antibodies. It’s not for recent infections—antibodies may take days to weeks to develop after exposure.
Why would my doctor order this test?
To investigate symptoms (e.g., bloody diarrhea), assess exposure risks, or support public health investigations (e.g., food recalls). It’s not a routine screening test unless symptoms or circumstances warrant it.
  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