Poster Presentation Lancefield International Symposium for Streptococci and Streptococcal Diseases 2025

Laboratory performance evaluation of three Strep A molecular point-of-care tests for settings at high risk of acute rheumatic fever (ARF) (#215)

Bernadette Wong 1 2 , Janessa Pickering 1 3 , Tanya Applegate 4 , Susan Matthews 5 , Jeffrey Canon 1 6 , Peter Richmond 1 2 7 , Asha Bowen 1 2 7
  1. Wesfarmer’s Centre for Vaccines and Infectious Diseases, The Kids Research Institute Australia, Nedlands, Western Australia, Australia
  2. Medical School, The University of Western Australia, Nedlands, Western Australia, Australia
  3. School of Biomedical Sciences, The University of Western Australia, Nedlands, WA, Australia
  4. Kirby Institute, The University of New South Wales, Sydney, New South Wales, Australia
  5. International Centre for Point-of-Care Testing, Flinders University, Adelaide, South Australia, Australia
  6. Centre for Child Health Research, The University of Western Australia, Nedlands, Western Australia, Australia
  7. Perth Children's Hospital, Perth, Western Australia, Australia

In remote Australia, Strep A molecular point-of-care tests (mPOCTs) are highly valued for their near-patient setup, high performance and rapid diagnosis of Strep A sore throats. We hypothesise that the high performance in US clinical studies will translate to high Strep A burden settings in Australia. We performed controlled laboratory testing for three Clinical Laboratory Improvement Amendment (CLIA)-waived Strep A mPOCTs – Cepheid Xpert® Xpress Strep A, Abbott IDNOW™ Strep A 2 and Roche Cobas® Strep A assay using samples of representative Strep A epidemiology.

We assessed the analytical sensitivity and specificity of three Strep A mPOCTs using retrospectively collected throat swabs, consented for future use from the Missing Piece Surveillance Study (MPSS, n=116) in the Kimberley region of Western Australia, where ARF prevalence is high. These swabs were a mix of healthy, asymptomatic, and symptomatic Strep A sore throat status previously characterised by culture and qPCR. Additionally, we included commensal isolates and external quality controls. Limit of detection was ascertained using the speB qPCR assay. Operator training was conducted to ensure familiarity with respective mPOCTs according to manufacturer’s instructions.

Positive test rates will be calculated for each test and compared against Strep A culture results to determine sensitivity and specificity. Final results will be presented at the conference.

Accurate performance of Strep A mPOCT remains critical for diagnosing Strep A sore throats in remote Australia, eliminating the need for confirmatory culture, which delays results by 5-7 days. This is crucial for facilitating timely antibiotic treatment to prevent ARF.