Streptococcal Serology Reference Intervals in an Australian Pediatric Cohort

Area of Science:

• Pediatric Immunology
• Microbial Diagnostics
• Clinical Serology

Background:

• Acute rheumatic fever and post-streptococcal glomerulonephritis are autoimmune complications of Streptococcus pyogenes infection.
• Serological evidence of preceding infection is key for diagnosis.
• Streptolysin O and deoxyribonuclease B are primary serological targets.

Purpose of the Study:

• To establish age-based reference intervals for anti-streptolysin O (ASO) and anti-deoxyribonuclease B (ADB) antibody levels.
• To guide the interpretation of serological tests in healthy Australian children.
• To support accurate diagnosis of Streptococcus pyogenes-related autoimmune conditions.

Main Methods:

• Collected serum samples from pediatric cohorts (32-week gestation to <18 years) in Melbourne, Australia.
• Measured ASO levels using turbidimetry (cohort 1) and nephelometry (cohort 2).
• Measured ADB levels using nephelometry (cohort 2), generating age-specific reference intervals and 80% upper limits of normal.

Main Results:

• ASO levels measured by turbidimetry peaked in children aged 5-9 years (80% ULN 346 IU/mL).
• Nephelometric ASO levels showed a linear age-related increase, peaking in adolescents (80% ULN 426 IU/mL).
• ADB levels measured by nephelometry were highest in children aged 10-14 years (80% ULN 454 IU/mL).

Conclusions:

• Established age-specific reference intervals for ASO and ADB levels using turbidimetry and nephelometry.
• Emphasized the need for local, method-specific, age-based reference intervals for accurate clinical interpretation.
• Aimed to improve diagnosis of acute rheumatic fever and post-streptococcal glomerulonephritis in children.