Antideoxyribonuclease-B Streptococcal Antibody

Synonym/Acronym

antiDNase-B streptococcal antibody, ADNase-B, AntiDNase-B.

Rationale

To assist in identifying a recent group A streptococcal infection by identification of antibodies.

Patient Preparation

There are no food, fluid, activity, or medication restrictions unless by medical direction.

Normal Findings

Method: Nephelometry.

Age		Normal Results
0–6 yr		Less than 250 units
7–17 yr		Less than 350 units
18 yr and older		Less than 260 units

Critical Findings and Potential Interventions ⬆ ⬇

Overview ⬆ ⬇

(Study type: Blood collected in a red-top tube; related body system: Immune system.)

The presence of streptococcal deoxyribonuclease (DNase)-B antibodies is an indicator of recent group A, beta-hemolytic streptococcal infection, especially if a rise in antibody titer can be shown. Because ASO titer may not become elevated in some patients who experience sequelae involving the skin or kidneys, the antideoxyribonuclease-B streptococcal test may be a better test for these patients. For this reason, health-care providers (HCPs) may request both ASO and the antideoxyribonuclease-B streptococcal test.

Anti-DNase B titers rise more slowly than ASO titers, peaking 4 to 8 wk after infection. They also decline much more slowly, remaining elevated for several months. A rise in titer of two or more dilution increments between acute and convalescent specimens is clinically significant.

For additional information regarding testing for group A beta-hemolytic streptococci, refer to the studies titled “Antistreptolysin O Antibody” and “Group A Streptococcal (GAS) Testing.” While the throat culture is still considered the “gold standard” for diagnosis, especially in the pediatric population, point-of-care molecular polymerase chain reaction methods exhibit high specificity with a rapid turnaround time (less than 10 min).

Indications ⬆ ⬇

Assist in diagnosis of serious complications that may develop after a recent strep A infection, such as glomerulonephritis or rheumatic fever.
Investigate the presence of streptococcal antibodies as a source of recent infection.

Interfering Factors ⬆ ⬇

Potential Medical Diagnosis: Clinical Significance of Results ⬆ ⬇

Increased In

Presence of antibodies, especially a rise in titer, is indicative of exposure.

Cellulitis
Endocarditis
Impetigo
Necrotizing fasciitis
Poststreptococcal glomerulonephritis
Rheumatic fever
Streptococcal infections (systemic—e.g., toxic shock syndrome)
Scarlet fever

Decreased In

N/A

Nursing Implications ⬆

Before the Study: Planning and Implementation

Teaching the Patient What to Expect

Explain that a blood sample is needed for the test. Discuss how this test can assist in documenting significant sequelae or complications associated with recent streptococcal infection.

Potential Nursing Actions

Confirm that ordered cultures have been completed prior to initiating antibiotic therapy if possible.

After the Study: Implementation & Evaluation Potential Nursing Actions

Treatment Considerations

Interventions/actions related to infection include the following: Promote good hygiene with assistance as needed. Handwashing is the best barrier to infection. Adhere to standard precautions. Implement isolation as appropriate. Ensure ordered cultures are submitted. Administer prescribed antibiotics and antipyretics to treat infection and fever (obtain ordered culture specimen before starting antibiotics if possible). Monitor and trend vital signs (B/P, HR, temperature, RR), early indicators of an altered status. Facilitate cooling measures to decrease temperature. Encourage oral fluids to support hydration and administer ordered IV fluids to support hydration and maintain homeostasis.

Clinical Judgement

Consider how to convince the reluctant patient to adhere to treatment recommendations related to infection and the potential devastating effects with a failure to comply. Serious thought should be given to individual worldview and cultural health practices.

Follow-Up Evaluation and Desired Outcomes

Understands that a convalescent specimen may be requested in 2 to 4 wk to assess disease progress and treatment effectiveness.
Acknowledges that to completely eradicate the infecting organism and prevent reinfection, it is necessary to complete the entire course of antibiotic therapy, even when signs and symptoms of infection are no longer present.