Invasive group A streptococcal disease surveillance in Canada, 2021-2022

Invasive group A streptococcal (iGAS, ) disease has been a nationally notifiable disease in Canada since 2000. This report summarizes the demographics, types, and antimicrobial resistance of iGAS isolates collected in Canada in 2021 and 2022. The Public Health Agency of Canada's National Microbiology Laboratory collaborates with provincial and territorial public health laboratories to conduct national surveillance of invasive . typing was performed using the Centers for Disease Control and Prevention sequencing protocol or extracted from whole-genome sequencing data. Antimicrobial susceptibilities were determined using Kirby-Bauer disk diffusion according to Clinical and Laboratory Standards Institute guidelines or predicted from whole-genome sequencing data based on the presence of resistance determinants. Overall, the incidence of iGAS disease in Canada was 5.56 cases per 100,000 population in 2021, decreasing from the peak of 8.6 cases per 100,000 population in 2018. A total of 2,630 iGAS isolates were collected during 2022, representing an increase from 2021 (n=2,179). In particular, there was a large increase in isolates collected from October to December 2022. The most predominant type overall in 2021 and 2022 was 49, at 21.5% (n=468) and 16.9% (n=444), respectively, representing a significant increase in prevalence since 2018 (