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Serum/plasma concentration of immunoglobulin G (IgG) antibodies against *Escherichia coli* O157:H7 (a specific bacterial pathogen)

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

This test measures the level of antibodies your body produces in response to infection with *E. coli* O157:H7, a rare but serious bacteria often linked to foodborne illness.

Quick summary

["Helps assess past exposure to this specific bacterial strain and may support diagnosis in suspected cases."]

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

Key facts at a glance

LOINC
29496-7
Short code
PA IgA Bld Ql FC
Synonyms
PA IgA Bld Ql FC
Category
hematology
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
flow-cytometry
CPT
82784
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 had symptoms like severe diarrhea, vomiting, or blood in your stool—common signs of *E. coli* O157:H7 infection. It’s also used in research or specialized diagnostic settings for monitoring exposure.

What to Expect Before the Test

No special preparation is needed. A blood sample is drawn from a vein, usually in your arm. The sample is then sent to a lab for testing.

What the Results Mean

Positive results indicate your immune system has detected and responded to the bacteria. However, a positive test alone doesn’t confirm active infection—other tests (like stool culture) may be needed for diagnosis.

Possible Causes of Positive Results

A positive IgG test could mean past exposure (e.g., from food, water, or contaminated surfaces) or vaccination. It doesn’t always indicate current illness, as antibodies may linger for months or years.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Anti-*E. coli* O157:H7 Antibody

Frequently asked questions

What does a positive result mean?
A positive result suggests your body has produced antibodies against *E. coli* O157:H7, meaning you’ve likely been exposed to the bacteria at some point. This doesn’t mean you’re currently sick, as antibodies can remain for a long time after infection.
No, this test alone cannot diagnose an active *E. coli* O157:H7 infection. Your doctor may order additional tests, such as a stool culture, to confirm current illness.
Results are typically available within 1–2 weeks, depending on the lab’s processing time. Your healthcare provider will discuss the results with you during your follow-up visit.
No special preparations are needed. However, if you’re on blood-thinning medication or have a history of bleeding disorders, let your provider know before the test.
If your results are unclear or positive, your healthcare provider may recommend further testing (like a stool culture) to determine if you have an active infection or if other factors are at play.
  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