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Escherichia coli (E. coli) bacterial culture and antibiotic susceptibility testing (serum/plasma)

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

This test checks for the presence of *Escherichia coli* bacteria in your blood and determines how your body might respond to antibiotics.

Quick summary

["Blood cultures help diagnose serious infections and guide antibiotic treatment."]

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

Key facts at a glance

LOINC
39019-5
Short code
E coli O157H7 Ag RawMilk Ql IA
Synonyms
E coli O157H7 Ag RawMilk Ql IA
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
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

A blood sample is collected to detect *E. coli* bacteria, which can cause infections like sepsis or bloodstream infections. The test also evaluates how different antibiotics might affect these bacteria, helping your healthcare provider choose the best treatment.

Why It’s Done

You may need this test if you have symptoms like fever, chills, or unexplained infections, or if you’re at higher risk (e.g., weakened immune system, recent surgery). Doctors use it to confirm infections and guide antibiotic use.

Sample Collection and Process

Blood is drawn from a vein, placed in special containers, and sent to a lab. Bacteria grow in the sample, and antibiotic effects are tested to identify the most effective treatment.

What to Expect

Results typically take 3–5 days, depending on lab methods. You’ll discuss findings with your doctor, who may recommend follow-up tests or adjustments to your treatment plan.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical significance: Positive results confirm *E. coli* infection, prompting urgent treatment to prevent complications like organ damage or death. Susceptibility data ensures antibiotics target the correct bacteria, reducing resistance risks.

Short name

E. coli Blood Culture

Frequently asked questions

How long will I wait for results?
Results usually arrive within 3–5 business days, depending on lab workflows. Your doctor will explain findings and next steps during your follow-up visit.
Can I take antibiotics before the test?
Yes, but inform your doctor immediately. Antibiotics may affect test accuracy or delay results. Stopping them could also change the outcome.
Does this test require fasting?
No fasting is needed. Blood is drawn at any time, but hydration may be encouraged to support vein access.
  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