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Antibody to Streptococcus pneumoniae (IgG) – Serum

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

This test measures the level of antibodies against *Streptococcus pneumoniae* (pneumococcus) in your blood. Antibodies help your immune system fight infections caused by this common bacterial pathogen.

Quick summary

["This test helps assess your immune response to pneumococcal bacteria, which can cause pneumonia, meningitis, or other serious infections."]

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

Key facts at a glance

LOINC
85740-9
Short code
S pneum Da 5 DNA Ct Spec Qn NAA+probe
Synonyms
S pneum Da 5 DNA Ct Spec Qn NAA+probe
Category
coagulation
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
probe-amp-tar
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 healthcare provider may order this test if you’ve had recent symptoms of pneumonia, meningitis, or other infections caused by *Streptococcus pneumoniae*. It may also be used in people with weakened immune systems, those who’ve received pneumococcal vaccines, or those at higher risk of infection.

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample, usually drawn from a vein in your arm. The process takes a few minutes, and you may feel slight discomfort, but it’s generally quick and safe.

What the Results Mean

Higher levels of pneumococcal antibodies suggest your immune system has recognized and responded to the bacteria. Lower or absent levels may indicate a reduced immune response, especially if you’ve had recent or ongoing infections.

Common Causes of Abnormal Results

Elevated levels may follow a pneumococcal infection or vaccination. Low or absent levels could reflect a weakened immune system, chronic illness, or prior exposure without infection.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Strep pneumoniae IgG antibody

Frequently asked questions

Will this test detect an active infection right now?
No, this test measures antibodies from past exposure or immune response—not active infection. If you suspect a current pneumococcal infection, your doctor may recommend additional tests, like blood cultures or imaging.
Can I get this test if I’ve had the pneumococcal vaccine?
Yes, this test can show whether your immune system produced antibodies after vaccination. It’s useful for assessing vaccine effectiveness, especially in people with weakened immune systems.
What if my results are low or normal?
Low or normal results may mean you haven’t been exposed recently or your immune system isn’t responding as expected. Your doctor may recommend further testing, vaccination, or monitoring depending on your health status.
  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