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E. coli-specific antibody (IgG) by immunoassay (serum/plasma)

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

This test measures the presence of antibodies against *Escherichia coli* bacteria in your blood, which your immune system produces in response to past or current infection.

Quick summary

["Helps identify immune response to E. coli bacteria, useful in diagnosing infections or guiding treatment decisions."]

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

Key facts at a glance

LOINC
21262-1
Short code
E coli SXT Stl Ql IA
Synonyms
E coli SXT Stl Ql IA
Category
chemistry
Sample
stool
Container
Clean container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
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 fever, stomach pain, diarrhea, or urinary issues that could suggest an E. coli infection. It may also be used to assess immune response after exposure or to monitor chronic conditions linked to bacterial exposure.

What to Expect Before the Test

No special preparation is needed. You’ll likely have a simple blood draw from a vein in your arm. The sample is sent to a lab for testing, and results are typically available within 1–3 business days.

What the Test Measures

The test detects IgG antibodies, a type of protein your immune system makes to fight off past infections. These antibodies don’t always indicate an active infection but can signal your body’s response to E. coli exposure.

Possible Results and Their Meaning

A positive result means your body has produced antibodies against E. coli, which could mean you’ve had an infection or been exposed before. A negative result suggests no detectable antibodies, which may or may not mean no past exposure.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

E. coli Antibody Test

Frequently asked questions

What does a positive result mean?
A positive result indicates your immune system has recognized E. coli, which could be due to a past infection, vaccination, or exposure. This may help confirm a diagnosis of urinary tract infection (UTI), food poisoning, or other E. coli-related illnesses. It can also guide treatment if you’re at risk for recurrent infections.
What does a negative result mean?
A negative result means no detectable antibodies were found in your blood. This doesn’t necessarily mean you’ve never been exposed to E. coli, as antibody levels can vary. It may also be useful if you’re being monitored for conditions like hemolytic uremic syndrome (HUS) or other immune-related disorders linked to bacterial exposure.
How long do results take?
Results are usually available within 1–3 business days, depending on your lab’s processing time. Your healthcare provider will discuss the results with you during your follow-up visit.
  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