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Escherichia coli O157:H7 Antibody, Immunoassay (Serum/Plasma)

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

This test detects antibodies in your blood that your immune system produces in response to a specific type of harmful bacteria called *Escherichia coli* (E. coli) O157:H7. It helps identify if you’ve been exposed to this strain, which can cause severe illness.

Quick summary

["This test helps track past exposure to a dangerous bacterial strain linked to food poisoning or waterborne outbreaks."]

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

Key facts at a glance

LOINC
6964-1
Short code
Y enterocol IgA Ser IA-aCnc
Synonyms
Y enterocol IgA Ser IA-aCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
CPT
82784
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

What This Test Measures

The test uses an immunoassay method to detect antibodies (immunoglobulins) produced by your immune system in response to *E. coli* O157:H7. These antibodies are a sign that your body has encountered this bacteria at some point, though they may not indicate an active infection.

Why It’s Done

Your healthcare provider may order this test if you’ve had symptoms of food poisoning (e.g., severe diarrhea, vomiting, stomach cramps) or if you’ve been exposed to contaminated food/water. It’s also used in outbreaks or after potential exposure to this bacteria.

How It Works

A small blood sample is taken and analyzed to detect the presence of antibodies specific to *E. coli* O157:H7. The test does not measure live bacteria but rather your immune system’s reaction.

What to Expect Before the Test

No special preparation is needed. You may have a slight bruise or discomfort at the needle site, but this usually fades quickly. If you’re pregnant, have a bleeding disorder, or take blood thinners, let your provider know.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Positive results suggest past exposure to *E. coli* O157:H7, which can cause serious illness (e.g., hemolytic uremic syndrome in children). However, antibodies may decline over time, so repeated testing may be needed. This test alone does not diagnose an active infection—other tests (e.g., stool cultures) may be needed for confirmation.

Short name

E. coli O157:H7 Antibodies

Frequently asked questions

Does this test show if I currently have E. coli O157:H7?
No. This test only detects antibodies your body made in response to the bacteria in the past. An active infection would require a separate stool or blood test.
How long does it take to get results?
Results are typically available within 1–3 business days, depending on your lab’s processing time.
Can I eat or drink before this test?
Yes, you can eat and drink normally. No fasting is required for this blood 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