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Antibody to *Escherichia coli* O157:H7 (serum/plasma)

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

This test detects antibodies in your blood that your immune system produces in response to *Escherichia coli* O157:H7, a type of harmful bacteria often linked to food poisoning.

Quick summary

["It helps identify if you’ve been exposed to this bacteria, which can cause severe illness."]

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

Key facts at a glance

LOINC
17792-3
Short code
ENA SS-A Ab Ser-aCnc
Synonyms
ENA SS-A Ab Ser-aCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
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 vomiting—especially after eating contaminated food. It’s also used in cases of suspected foodborne illness outbreaks or if you’ve been exposed to someone with E. coli infection.

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample, usually drawn from your arm. If you’re tested for exposure in the past, your results may show antibodies even if you’re currently symptom-free.

What the Results Mean

Positive results indicate your immune system has recognized and fought *E. coli* O157:H7. Negative results mean no detectable antibodies were found at this time, but you may still be at risk if exposed recently. Follow-up testing or stool samples may be needed for diagnosis.

Common Causes of False Results

False positives or negatives can occur due to recent exposure, cross-reacting antibodies, or testing errors. Your provider will discuss results in context with your symptoms and medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

E. coli O157:H7 Antibody Test

Frequently asked questions

What does this test measure?
This test measures the presence of antibodies (immunoglobulins) produced by your immune system in response to *E. coli* O157:H7 infection. Antibodies are proteins that help your body recognize and fight foreign invaders like bacteria.
How soon after exposure can I expect results?
Antibodies typically develop within 1–2 weeks after exposure to *E. coli* O157:H7. However, some people may not develop detectable antibodies for up to 4 weeks. Results may take several days to a week to process, depending on lab procedures.
Can I get this test at home?
No, this test is performed in a clinical laboratory using a blood sample drawn by a healthcare professional. Home testing kits for foodborne pathogens are not available for this specific test.
  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