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Quantitative Culture for Microbial Identification and Susceptibility (Blood)

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

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

Quick summary

["Helps diagnose infections and guide treatment choices based on what microbes are found."]

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

Key facts at a glance

LOINC
16134-9
Short code
N men Spec Ql Cult
Synonyms
N men Spec Ql Cult
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
organism-specific-culture
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

Why This Test Is Done

Your doctor may order a blood culture if you have symptoms like fever, chills, or unexplained infections. It’s also used to confirm infections in people with weakened immune systems or those receiving medical treatments that increase infection risk.

How the Test Works

A small sample of your blood is collected and placed in special containers that support bacterial or fungal growth. Over 48–72 hours, the lab checks for signs of infection and identifies any microbes present.

What to Expect During the Procedure

You’ll have a needle inserted into a vein (usually in your arm) to draw blood. The process is quick and may cause mild discomfort. You’ll be able to go about your usual activities afterward.

Possible Results and Next Steps

If microbes are found, your doctor will work with the lab to determine the best antibiotic treatment. If no microbes are detected, further testing may be needed to rule out other causes of your symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Blood cultures are critical for diagnosing serious infections like sepsis, endocarditis, or bloodstream infections. Accurate identification of the causative organism helps tailor antibiotic therapy to effectively treat the infection and prevent complications.

Short name

Blood Culture with Antimicrobial Susceptibility

Frequently asked questions

How long does it take to get results from a blood culture?
Results typically take 48 to 72 hours, though some cases may require longer. Your doctor will contact you if an infection is suspected or if further testing is needed.
Can I take antibiotics before my blood culture?
No, antibiotics can interfere with the test. If you’ve been prescribed antibiotics, tell your doctor before the procedure to avoid delaying treatment for an infection.
What if my blood culture comes back negative but I still feel sick?
A negative result doesn’t always mean you’re infection-free. Other causes of symptoms, like inflammation or other medical conditions, may need to be evaluated. Follow-up testing or additional blood cultures may be recommended.
  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