Poster Presentation Lancefield International Symposium for Streptococci and Streptococcal Diseases 2025

School and clinical-based experimentation to ascertain Streptococcus pyogenes (Strep A)  transmission (#5)

Stephanie L Enkel 1 2 , Thel Hla 1 2 3 , Bernadette Wong 2 , Janessa Pickering 2 4 , Liam Bedford 2 , Hannah Thomas 2 , Nina Lansbury 5 , Jonathan Carapetis 2 6 , Laurens Manning 1 2 3 , Asha Bowen 2 6
  1. Medical School, University of Western Australia, Nedlands, Western Australia, Australia
  2. The Kids Research Institute Australia, Nedlands, WA, Australia
  3. Department of Infectious Diseases, Fiona Stanley Hospital, Murdoch, WA, Australia
  4. Marshall Centre for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Nedlands, WA, Australia
  5. School of Public Health, University of Queensland, Brisbane, QLD, Australia
  6. Department of Infectious Diseases, Perth Children's Hospital, Nedlands, WA, Australia

Background: Streptococcus pyogenes (Strep A) is primarily transmitted via respiratory droplets, but knowledge about aerosol or environmental transmission remains limited. Understanding these mechanisms is crucial to designing effective interventions, especially in endemic regions. This study investigated Strep A transmission in an urban clinical setting and environmental presence in two remote Western Australian schools.

 

Methods: Sub-studies were embedded within the CHIPS Trial, exploring optimal penicillin dosing for Strep A pharyngitis prevention, and the Missing Piece Study, examining Strep A pharyngitis and impetigo burden in remote-living children.

 

Results: In the CHIPS Trial, 16 participants were assessed over 10 days with a mix of experimentation completed to determine transmissibility. 420 swabs of high-touch surfaces were collected, alongside 96 Colistin Nalidixic Acid (CNA) agar plates. Only one CNA plate (30 cm from a symptomatic participant) tested positive for Strep A.

 

In Kimberley schools, 240 swabs were collected from 12 classrooms during 2021–2022. Four swabs across three classrooms (one school, 2022) tested positive for Strep A. Strep A was not detected on any of the 84 CNA plates placed to assess airborne transmission. Whole genome sequencing revealed common Strep A strains circulating in Kimberley schools.

 

Conclusions: Strep A was detected on classroom surfaces but not via airborne sampling. Findings emphasise the importance of preventing infections to reduce the risk of life-threatening illness, keeping children healthy, out of hospital, and on Country. Results from ongoing genomic analyses will further inform transmission prevention strategies.