Challenges and insights in self-swab surveillance for asymptomatic Streptococcus pyogenes carriage

Asymptomatic carriage of Streptococcus pyogenes (Strep A) may contribute to transmission, yet its role remains poorly understood and evidence on optimal detection methods is limited. While self-collected throat swabs are used in infectious disease surveillance, their value for identifying asymptomatic Strep A carriage in adults is uncertain. This pilot prospective cohort study, conducted at a Perth medical research institute between August and October 2024, assessed feasibility and acceptability of self-collection, with sensitivity as a secondary objective. Adults aged ≥ 18 years without sore throat symptoms were eligible, and 120 participants were targeted based on an anticipated 5–10% carriage prevalence. In total, 65 participants were enrolled, all providing investigator-collected screening swabs analysed by point-of-care testing (PoCT) and culture. One participant (1.5%) tested PoCT-positive, but none of the 31 follow-up swabs were culture-positive. Swabbing was well tolerated and compliance was high. Recruitment challenges and lower-than-expected prevalence limited the study’s scope and prevented sensitivity evaluation. Nonetheless, the findings provide important lessons on feasibility, acceptability, and study design, highlighting the value of reporting negative results to guide future surveillance in higher-prevalence settings such as schools.