Description
When infected with Group A Streptococcus bacteria (GAS), the body produces antibodies to fight various enzymes released by the bacteria. One of these major enzymes is Deoxyribonuclease B (Dnase B). This test measures the level of antibodies circulating in the blood that are specifically targeting Dnase B. The presence of elevated Anti Dnase B antibodies indicates that the body was recently exposed to and fought a GAS infection.
Clinical Significance:
- Diagnosing Post-Streptococcal Complications: This test is crucial for patients presenting with symptoms of rheumatic fever or acute kidney inflammation (glomerulonephritis) weeks after a sore throat or skin infection has resolved.
- Superior Sensitivity for Skin Infections (Pyoderma/Impetigo): While the common ASO (Antistreptolysin O) titre is sensitive to strep throat, Anti Dnase B is significantly more sensitive and reliable for detecting GAS infections that originated in the skin, which may not raise ASO levels as predictably.
- Paired Screen: It is often ordered alongside the ASO titre to increase the overall sensitivity of detecting a recent strep infection to over 90%. If either is elevated, a recent infection is likely.
When is this test recommended?
Healthcare providers typically order the Anti Dnase B test when:
- A patient shows signs of rheumatic fever (e.g., heart palpitations, joint pain/swelling, fever, chorea) or glomerulonephritis (e.g., blood in urine, decreased urine output, swelling around the eyes).
- A physician needs to confirm if a patient had a recent Group A Strep infection, particularly if they previously had a negative throat culture during the acute illness.
Sample Requirements:
- Specimen: Blood (Serum).
- Container: A standard Gold-top Serum Separator Tube (SST) (as pictured). The gold plug separates the serum from the clot activator.
Patient Preparation:
- General: Typically, no fasting is required. Patients can eat and drink normally before the test. It is essential to inform your doctor about all recent bacterial infections and any antibiotics taken.
