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Bacterial Culture with Antibiotic Susceptibility Testing (Serum/Plasma)

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

This test checks whether bacteria in your bloodstream are responding to specific antibiotics, helping your doctor choose the best treatment.

Quick summary

["Determines which antibiotics may effectively fight bacterial infections in your blood."]

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

Key facts at a glance

LOINC
33570-3
Short code
ENA SS-B Ab Ser IB-aCnc
Synonyms
ENA SS-B Ab Ser IB-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
ib
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 involves growing bacteria from your blood sample in a controlled environment and then testing how different antibiotics affect their growth. This helps identify if the bacteria are resistant or sensitive to common medications.

Why It’s Done

Your doctor may order this test if you have signs of a serious blood infection (sepsis) or if you’re receiving antibiotics but symptoms persist, suggesting the bacteria may be resistant to the current treatment.

How It Works

A small blood sample is taken and cultured to isolate bacteria. Once identified, antibiotic discs or strips are applied to detect bacterial growth inhibition, indicating sensitivity or resistance to specific antibiotics.

Preparation

No special preparation is needed. You may have a slight bruise or soreness at the needle site, but this usually goes away quickly.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Serum Antibiotics Sensitivity Test

Frequently asked questions

This test is critical for tailoring antibiotic therapy to target the specific bacteria causing your infection, reducing unnecessary side effects and improving recovery chances.
Antibiotics that show no growth inhibition on the test may not be effective for your infection, so your doctor will adjust treatment accordingly.
How long will results take?
Results typically take 2–5 business days, depending on lab processing times and bacterial growth rates. Your doctor will contact you once they’re ready.
Can I take antibiotics before this test?
If you’re already on antibiotics, stop them for at least 24 hours before the test to ensure accurate results. Always follow your doctor’s instructions.
  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