Serum or plasma concentration of pneumococcal polysaccharide antigen (via immunoassay)

What This Test Measures

The test detects specific antigens from *Streptococcus pneumoniae*, a common bacteria that can cause pneumonia, meningitis, or bloodstream infections. These antigens are fragments of the bacteria’s outer cell wall that your immune system recognizes. If present, they suggest recent bacterial exposure or infection.

Why It’s Done

Your healthcare provider may order this test if you have symptoms like fever, chills, or confusion, especially if you’ve been exposed to pneumococcal bacteria or have a weakened immune system. It can also be used in research or clinical trials studying pneumococcal vaccines or treatments.

Sample Collection and Preparation

A blood sample is taken from a vein (usually in your arm). The blood is processed to separate serum or plasma, which is then tested for pneumococcal antigens using an immunoassay method. This method detects the presence of these antigens without needing to grow the bacteria in a lab.

What to Expect Before the Test

No special preparation is needed, but inform your provider about any medications (especially antibiotics) or recent illnesses you’ve had. Avoid vigorous exercise or eating heavy meals before the blood draw.