To determine invasive group A Streptococcus trends in Canada, we characterized emm1 isolates collected during 2018-2023. The percentage of hypervirulent M1UK lineage isolates increased significantly, from 22.1% in 2018 to 60.2% in 2023. Genomic analysis identified geographically and temporally associated clusters and genes associated with virulent bacteriophage acquisition.
Keywords: Canada; M1UK; Streptococcus pyogenes; antimicrobial resistance; bacteria; emm1; group A Streptococcus; scarlet fever.