Serum or plasma concentration of pneumococcal antigen (qualitative screening)

What This Test Measures

The test looks for specific proteins (antigens) produced by *Streptococcus pneumoniae* bacteria. If these antigens are found, it suggests an active infection. This is typically done using an immunoassay method to detect the presence of these markers in your blood or serum/plasma sample.

Why It’s Done

Your healthcare provider may order this test if you have symptoms like high fever, chills, confusion, difficulty breathing, or signs of pneumonia, sepsis, or meningitis—especially if you’re at higher risk (e.g., elderly, immunocompromised, or with chronic health conditions). It can also be used in certain clinical settings to confirm or monitor suspected pneumococcal infections.

How It Works

A small blood sample is taken from your arm. The serum or plasma portion is then analyzed in a lab using an immunoassay technique to detect pneumococcal antigens. The result is qualitative (positive or negative) rather than quantifying the exact amount of bacteria.

What to Expect Before the Test

No special preparation is needed, but inform your provider if you’re taking blood-thinning medications or have bleeding disorders. Avoid alcohol for 24 hours before testing if instructed.