Poster Presentation Lancefield International Symposium for Streptococci and Streptococcal Diseases 2025

Comparative analysis of Strep A bacterial detection methods in an Australian paediatric urban pharyngitis surveillance study   (#211)

Anna Takahashi 1 2 3 , Jasmyn Voss 1 4 , Serene Yeow 1 4 , ZiYing Ng 1 2 3 , Andrew Hayes 5 , Michael Morici 1 2 3 , Elizabeth Negus 1 2 3 , Hannah Frost 1 4 , Ciara Baker 4 , Tria Williams 4 , Maria Emilia Duenas 1 2 3 6 , Mark Davies 5 , Andrew Steer 1 4 , Jonathan Carapetis 1 2 3 6 7 , Alma Fulurija 1 2 3 6
  1. The Australian Strep A Vaccine Initiative, Nedlands, Western Australia, Australia
  2. The Kids Research Institute Australia, Nedlands, Western Australia, Australia
  3. Wesfarmers Centre for Vaccines and Infectious Diseases, Nedlands, Western Australia, Australia
  4. Murdoch Children's Research Insitute, Parkville, Victoria, Australia
  5. The University of Melbourne, Parkville, Victoria, Australia
  6. The University of Western Australia, Nedlands, Western Australia, Australia
  7. Perth Children's Hospital, Nedlands, Western Australia, Australia

Background:  

Despite the significant burden Strep A imposes, no licensed vaccines are currently available, and surveillance data for paediatric non-invasive Strep A pharyngitis remain limited. The Australian Strep A Vaccines Initiative (ASAVI) aims to develop accurate and robust surveillance for pharyngitis, Strep A carriage, and circulating strain serotypes to establish the baseline epidemiology of Strep A pharyngeal infection as a first step to advance in a vaccine clinical trial. 

Methods: 

In 2021, ASAVI conducted a Strep A surveillance 12-month study in Melbourne and Perth with 474 healthy children (aged 3-14) completed study. A total of 1,924 throat swabs were collected at baseline, seasonally, and upon onset of sore throat symptoms (STS). Swabs were cultured to assess pharyngitis incidence, carriage prevalence, and strain diversity in two research laboratories for site comparability. Swabs were analysed using standard bacterial culture on blood agar, broth culture enrichment and isothermal nucleic acid amplification Point-Of-Care test (POCT).   

Results: 

Out of 372 STS swabs, 33% (n=123) tested Strep A positive by POCT. Among these, 78% were confirmed on blood agar plate. Standard bacterial culture showed low sensitivity for low bacterial load samples, with broth enrichment improving detecting by 5.1%.  

Conclusion: 

The study found that active surveillance using POCT enhances detection rates of Strep A, indicating their potential utility in clinical settings with its short diagnosis time, high sensitivity and accuracy with a low load of throat swab samples. These results highlight the importance of ongoing surveillance and development of robust methods to support future vaccine trials.