What should be done next after a negative streptozyme test in a patient with clinical signs of a streptococcal throat infection?

After obtaining a negative streptozyme test in a patient who presents with clinical signs of a streptococcal throat infection, the next best step is to perform either anti-streptolysin O (ASO) or anti-deoxyribonuclease B (anti-DNase B) testing. This is appropriate because a negative streptozyme test does not rule out streptococcal infection, as it may occur in cases where the serological response has not yet developed.

ASO testing detects antibodies produced in response to streptococcal infection, specifically to streptolysin O, which is a toxin produced by the bacteria. Similarly, anti-DNase B testing identifies antibodies against deoxyribonuclease B, another enzyme produced by Group A Streptococcus. These tests are useful for confirming a diagnosis when a streptozyme test is negative but there is still a strong clinical suspicion of infection.

In contrast, repeating the streptozyme test using diluted serum may not provide additional valuable information since the original test was negative. Antihyaluronidase testing is less commonly used and not specifically indicated in this context. Waiting 3-5 days to repeat the streptozyme test may delay appropriate