Virtual Poster 21st Lancefield International Symposium for Streptococci and Streptococcal Diseases 2022

Preceding group A streptococcus skin and throat infections are individually associated with acute rheumatic fever: evidence from New Zealand (#221)

Jane Oliver 1 , Julie Bennett 2 , Sally Thomas 2 , Jane Zhang 2 , Nevil Pierse 2 , Nicole J Moreland 3 , Deborah A Williamson 4 , Susan Jack 5 6 , Michael G Baker 2
  1. University of Melbourne & Murdoch Children's Research institute, Melbourne, VIC, Australia
  2. Public Health, University of Otago wellington, Wellington, New Zealand
  3. Molecular Medicine and Pathology, University of Auckland, Auckland, New Zealand
  4. Infectious Diseases, University of Melbourne, Melbourne, Victoria, Australia
  5. Department of Preventive and Social Medicine, University of Otago, Dunedin, New Zealand
  6. Southern District Health Board, Dunedin, New Zealand

Introduction 

Acute rheumatic fever (ARF) is usually considered a consequence of group A streptococcus (GAS) pharyngitis, with skin infections not considered a major trigger. The aim was to quantify the risk of ARF following a GAS-positive skin or throat swab.

Methods 

Pre-existing administrative data was obtained. Throat and skin swab data (1,866,981 swabs) from the Auckland region, New Zealand and antibiotic dispensing data were analysed (2010–2017). Incident ARF cases were identified using hospitalisation data (2010–2018). The risk ratio (RR) of ARF following swab collection was estimated. Antibiotic dispensing data were linked to investigate whether this altered ARF risk following GAS detection.

Results 

ARF risk increased following GAS detection in a throat or skin swab. Māori and Pasifika had the highest ARF risk 8–90 days following a GAS-positive throat or skin swab, compared with a GAS-negative swab. During this period, the RR for Māori and Pasifika following a GAS-positive throat swab was 4.8 (95%CI 3.6-6.4) and following a GAS-positive skin swab, the RR was 5.1 (95%CI 1.8-15.0). Antibiotic dispensing was not associated with a reduction in ARF risk following GAS detection in a throat swab (antibiotics not dispensed (RR: 4.1, 95% CI 2.7-6.2), antibiotics dispensed (RR: 4.3, 95% CI 2.5-7.4) or in a skin swab (antibiotics not dispensed (RR: 3.5, 95% CI 0.9-13.9), antibiotics dispensed (RR: 2.0, 95% CI 0.3-12.1).

Conclusions 

A GAS-positive throat or skin swab is strongly associated with subsequent ARF, particularly for Māori and Pasifika. This study provides the first population-level evidence that GAS skin infection can trigger ARF.