Oral Presentation 21st Lancefield International Symposium for Streptococci and Streptococcal Diseases 2022

The performance of a rapid molecular point-of-care test for Strep A pharyngitis in remote-living children at high risk of acute rheumatic fever (#53)

Dylan D Barth 1 2 , Gelsa Cinanni 1 , Robyn MacArthur 1 , Bernadette Wong 1 , Janessa Pickering 1 , Scott Winslow 1 , Slade Sibosado 1 , Liam Bedford 1 , Jonathan Carapetis 1 2 3 , Asha C Bowen 1 2 3
  1. Wesfarmer’s Centre for Vaccines and Infectious diseases, Telethon Kids Institute, Perth, Western Australia, Australia
  2. Faculty of Health and Medical Sciences, University of Western Australia, Perth, Western Australia, Australia
  3. Department of Infectious Diseases, Perth Children’s Hospital, Perth, Western Australia, Australia

Background

Accurate and timely diagnosis of StrepA pharyngitis in remote settings is challenging. The availability of molecular point-of-care (PoC) testing for Strep A pharyngitis may revolutionise prevention strategies in children at high risk of acute rheumatic fever (ARF). We aimed to evaluate the performance of a rapid molecular PoC test for StrepA pharyngitis in remote-living children in the Western Australia (WA).

 

Methods

The Missing Piece Study is a prospective surveillance program to determine the epidemiology of StrepA infection in the Kimberley WA, comprising: (1) cross-sectional screening two times a year, and (2) weekly active surveillance visits once a week. We collected two throat swabs for microbiological culture and PoC testing using the Strep A ID NOW machine, respectively. We calculated the sensitivity, specificity, positive (PPV) and negative predictive values (NPV). The PoC test performance was compared to the gold standard microbiological culture results. Prevalence estimates are based on culture results.

 

Results

A total of 124 children participated in four screening visits and the active weekly surveillance period over a 6-month period between April and September 2021. The overall culture-confirmed prevalence of StrepA pharyngitis was 18.8% (95% confidence interval [CI] 9.4 – 28.1%) during screening visits. The period prevalence was 6.7% (95% CI, 0 – 15.6%) over the active surveillance period. We calculated sensitivity 75.0%, specificity 86.7%, PPV 42.9% and NPV 96.3% of the molecular PoC test.

 

Conclusions

Our results show StrepA pharyngitis is more common than previously reported. We confirm the value and feasibility of molecular PoC testing in remote Australian settings to improve diagnosis and treatment of StrepA pharyngitis.