Overview
Anti-DNase B (Anti-Deoxyribonuclease B) is an antibody produced by the immune system in response to an infection caused by Group A Streptococcus (GAS). The document explains that this antibody targets the extracellular streptococcal enzyme DNase B. Anti-DNase B is especially important when diagnosing infections where the ASO (Anti-Streptolysin O) test may be negative—particularly streptococcal skin infections such as pyoderma, impetigo, and cellulitis.
The immune response begins 1–6 weeks after infection, and elevated Anti-DNase B levels indicate recent exposure to GAS. The antibody is useful for confirming immune-related complications like acute rheumatic fever and post-streptococcal glomerulonephritis, especially when the original infection was mild or subclinical.
Clinically, Anti-DNase B testing measures the amount of streptococcal antibody present in blood and is often used alongside ASO to improve diagnostic accuracy. The document highlights several testing methodologies, including Nephelometric methods, ELISA, turbidimetry, and latex agglutination.
Symptoms
Symptoms do not arise from Anti-DNase B itself; instead, they reflect the secondary complications of untreated or unrecognized streptococcal infections. The document illustrates the common presenting symptoms seen in conditions linked with elevated Anti-DNase B titers.
Common symptoms associated with glomerulonephritis include:
- Hematuria
- Edema
- Hypertension
Symptoms linked with rheumatic fever include:
- Fever
- Polyarthritis
- Carditis
- Chorea
- Skin rash
- Subcutaneous nodules
These symptoms serve as indicators for clinicians to perform Anti-DNase B testing to confirm whether a recent GAS infection may be responsible for the immune-driven condition.
Causes
The document outlines that Anti-DNase B rises in response to Group A Streptococcus infection, particularly in the following contexts:
1. Throat Infections
GAS causes strep throat and other upper respiratory infections, stimulating antibody production.
2. Skin Infections
Anti-DNase B is especially sensitive for diagnosing skin infections such as:
- Pyoderma
- Impetigo
- Cellulitis
In these cases, ASO levels may remain low, making Anti-DNase B the preferred antibody marker.
3. Subclinical Infections
Some GAS infections go unnoticed. Anti-DNase B helps detect such hidden infections, especially when complications arise without a known history of sore throat or skin infection.
4. Post-Streptococcal Complications
Conditions like acute rheumatic fever or glomerulonephritis occur when the immune system reacts abnormally after a GAS infection. Anti-DNase B titers provide evidence of recent exposure.
The document notes that high titers (≥500 U/mL) strongly confirm a recent streptococcal infection and correlate with a higher risk of complication development.
Risk Factors
Risk factors for elevated Anti-DNase B are tied to exposure, untreated infections, and susceptibility to immune complications:
1. Recent or Unrecognized GAS Infections
Individuals with undiagnosed throat or skin infections are more likely to show elevated antibody levels.
2. Symptoms Suggestive of Rheumatic Fever
Fatigue, chest pain, shortness of breath, fever, and joint pain increase the likelihood of underlying streptococcal exposure.
3. Signs of Glomerulonephritis
Edema, dark urine, and high blood pressure raise suspicion of post-streptococcal renal involvement.
4. Children and Adolescents
The document mentions that reference ranges differ for children, who often experience more streptococcal infections.
5. Untreated or Improperly Treated GAS Infections
Failure to treat the infection increases the risk of immune-mediated complications that may occur days or weeks later.
6. Individuals in Close-Contact Settings
Crowded environments increase exposure to streptococcal bacteria.
Prevention
Prevention focuses on reducing the likelihood of complications, ensuring timely testing, and supporting accurate diagnosis:
1. Early Recognition and Treatment of GAS Infections
Identifying throat and skin infections promptly helps prevent complications associated with high Anti-DNase B levels.
2. No Special Test Preparation Needed
The document states that no specific preparation is required, enabling easy screening when symptoms appear.
3. Correct Sample Collection
A 3.0 mL blood sample should be collected in a plain red-capped tube with serum separated as early as possible to ensure test accuracy.
4. Monitor Patients with Suggestive Symptoms
Those showing signs of rheumatic fever or glomerulonephritis should be evaluated with Anti-DNase B testing even if the original infection went unnoticed.
5. Use Reliable Testing Methods
The document lists ELISA, latex agglutination, nephelometry, and turbidimetry as validated methods for accurate estimation.
6. Avoid Overtreatment
Monitoring titers over time helps determine whether the infection has resolved, preventing unnecessary antibiotic use.
