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Capsular Serotyping of Streptococcus pneumoniae Using the Quellung Reaction
Published on: February 24, 2014
Streptococcal Serology Reference Intervals in an Australian Pediatric Cohort
Shu Ki Tsoi1,2, Sharon Choo3, Lai-Yang Lee4
1Department of Infectious Diseases, The Royal Children's Hospital Melbourne, Parkville, Victoria, Australia.
Insights
This study establishes age-specific reference intervals for anti-streptolysin O (ASO) and anti-deoxyribonuclease B (ADB) antibody levels in Australian children. These findings are crucial for accurately diagnosing acute rheumatic fever and post-streptococcal glomerulonephritis.
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.
Background:
Diagnostic criteria for acute rheumatic fever and post-streptococcal glomerulonephritis, the 2 major autoimmune complications of Streptococcus pyogenes infection, include serological evidence of preceding infection. The S. pyogenes proteins, namely streptolysin O and deoxyribonuclease B, are the most widely used targets for clinical streptococcal serology. We aimed to establish age-based reference intervals (RIs) for healthy children in Victoria, Australia, to guide interpretation of anti-streptolysin O (ASO) levels measured by turbidimetry and nephelometry, and anti-deoxyribonuclease B (ADB) levels by nephelometry.
Methods:
Serum samples were collected from healthy pediatric cohorts aged 32-week gestation to <18 years at 4 hospitals in Melbourne, Australia, between February 2015 and October 2018. Anti-streptolysin O levels were measured in 2 cohorts: by turbidimetry in cohort 1 and by nephelometry in cohort 2. Anti-deoxyribonuclease B levels were measured by nephelometry in cohort 2. Reference intervals (RIs) for each age group were generated, including 80% upper limit of normal (ULN) cut-offs.
Results:
Anti-streptolysin O levels were measured by turbidimetry for 359 samples from cohort 1, and ASO and ADB levels were measured by nephelometry for 360 samples from cohort 2. Anti-streptolysin O levels, measured by turbidimetry, were highest in children 5-9 years of age (80% ULN 346 IU/mL) in cohort 1. For cohort 2, there was a linear age-related increase in ASO levels measured by nephelometry (80% ULN 426 IU/mL in those 15 to <18 years old) and ADB levels were highest in children aged 10-14 years (80% ULN 454 IU/mL).
Conclusions:
We established age-specific RI for ASO and ADB levels measured by turbidimetry and nephelometry for healthy Australian children. This study highlights the importance of local method-specific age-based RI to interpret ASO and ADB levels when clinicians suspect acute rheumatic fever or post-streptococcal glomerulonephritis in children.
