Streptococcus Group B Antigen Detection

Streptococcus Group B Antigen Detection

What it is

The Streptococcus Group B Antigen Detection test identifies the presence of Group B Streptococcus (GBS) antigens in a sample, usually taken from vaginal, rectal, urine, or body fluids. Group B Streptococcus is a type of bacteria commonly found in the gastrointestinal and genital tracts. While often harmless in healthy adults, it can cause serious infections in newborns, pregnant women, and individuals with weakened immune systems.

Uses

This test is used to:

• Screen pregnant women for Group B Streptococcus colonization, usually in late pregnancy (35–37 weeks).
• Detect GBS infection in newborns with suspected sepsis, meningitis, or pneumonia.
• Identify GBS in adults with urinary tract infections or bloodstream infections.
• Support rapid diagnosis in emergency cases where immediate results are needed.
• Guide preventive treatment with antibiotics during labor in GBS-positive mothers.

Symptoms / Conditions That May Lead to the Test

Doctors may recommend this test if:

• You are pregnant and undergoing routine prenatal screening for GBS.
• A newborn shows symptoms of sepsis, breathing difficulty, or fever shortly after birth.
• You have urinary tract infection symptoms during pregnancy.
• You have fever, pelvic pain, or prolonged rupture of membranes during labor.
• An individual with a weakened immune system shows signs of bloodstream or soft tissue infection.

Abnormal Results

• Positive Result: Indicates the presence of Group B Streptococcus antigens. In pregnant women, this typically leads to antibiotic prophylaxis during labor to prevent transmission to the newborn. In newborns or immunocompromised patients, it confirms infection and guides antibiotic therapy.
• Negative Result: Suggests no detectable GBS antigens. However, culture testing may still be done for confirmation, as antigen detection has lower sensitivity in some cases.

Results are often confirmed with culture, which remains the gold standard for diagnosis.

Risks

The test is safe and risk-free. Risks are related only to sample collection, which may involve:

• Mild discomfort during vaginal or rectal swab collection.
• Minimal risk of contamination if not collected properly.
• In newborns, slight discomfort when collecting body fluids for testing.