Comparison of group A streptococcal titres in healthy children and those with pharyngitis and skin infections

Julie Bennett*, Nicole J. Moreland, Deborah A. Williamson, Jonathan Carapetis, Julian Crane, Alana L. Whitcombe, Susan Jack, Matire Harwood, Michael G. Baker

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

Objectives: Rates of acute rheumatic fever, a sequelae of group A Streptococcal (GAS) infection, remain unacceptably high in Indigenous Māori and Pacific children in New Zealand. This prospective study aimed to describe GAS antibody titres in healthy children (5–14 years) by ethnicity, and to determine how paired titres vary with GAS culture positive and negative pharyngitis, and GAS skin infections. Methods: Analysis included 887 children (32% Māori, 36% Pacific, 33% European/Other) from Auckland, New Zealand. Cases comprise 772 children who had a sore throat or skin infection, which resulted in a swab taken for culture. Healthy controls were asymptomatic (N = 154) and matched by age, ethnicity and region. All participants had a serum sample, with a second sample collected from cases only. Sera were analysed for anti-streptolysin O (ASO) and anti-DNase-B (ADB) antibodies. Results: Healthy Māori and Pacific children had higher GAS antibody titres than healthy European/Other children. Children with GAS-positive sore throat had the highest mean ASO titres and children with GAS-positive skin infection had the highest mean ADB titres. When a two-fold increase or an upper limit of normal cut-off (ASO 450 IU/ml, ADB 400 U/ml) was applied to titres from children with GAS-positive sore throat, 62.1% were classified as having serologically confirmed GAS pharyngitis and 37.9% had GAS detected without serological response. Conclusions: Elevated ASO titres were associated with GAS pharyngitis and elevated ADB titres were associated with GAS skin infections in New Zealand children. Higher ASO/ADB titres in healthy Māori and Pacific children could indicate a greater prior exposure to GAS infections.

Original languageEnglish
Pages (from-to)24-30
Number of pages7
JournalJournal of Infection
Volume84
Issue number1
DOIs
Publication statusPublished - Jan 2022
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2021

Keywords

  • Anti-DNase-B
  • Anti-streptolysin O
  • Children
  • Group A Streptococcus
  • Pharyngitis
  • Serology
  • Skin infection

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