What is the role of the streptozyme test in the workup of acute poststreptococcal glomerulonephritis (APSGN)?

Updated: Dec 05, 2018
  • Author: Rajendra Bhimma, MBChB, MD, PhD, DCH (SA), FCP(Paeds)(SA), MMed(Natal); Chief Editor: Craig B Langman, MD  more...
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Answer

Recent poststreptococcal infection is most commonly demonstrated by serologic markers for elevated antibodies to extracellular streptococcal antigens. The streptozyme test, which measures 5 different streptococcal antibodies, is positive in more than 95% of patients with APSGN due to pharyngitis. However, sensitivity drops to 80% if APSGN follows pyoderma. The streptococcal antibodies measured include the following:

  • Antistreptolysin (ASO)

  • Antihyaluronidase (AHase)

  • Antistreptokinase (ASKase)

  • Antinicotinamide-adenine dinucleotidase (anti-NAD)

  • Anti-DNAse B antibodies

Apart from antistreptokinase (ASKase), all other streptococcal antibodies are commonly elevated after a pharyngitis, whereas only anti-DNAase B and AHase titers are typically increased after pyoderma. Thus, if only an ASO titer is used to screen for APSGN after skin infections, it may be falsely low or negative, and if the patient has received prior antibiotic treatment for a pharyngitis, this may blunt the rise in ASO titer.


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