Rapid expansion and international spread of M1UK in the post-pandemic UK upsurge of Streptococcus pyogenes

Ana Vieira, Yu Wan, Yan Ryan, Ho Kwong Li, Rebecca L. Guy, Maria Papangeli, Kristin K. Huse, Lucy C. Reeves, Valerie W.C. Soo, Roger Daniel, Alessandra Harley, Karen Broughton, Chenchal Dhami, Mark Ganner, Marjorie A. Ganner, Zaynab Mumin, Maryam Razaei, Emma Rundberg, Rufat Mammadov, Ewurabena A. MillsVincenzo Sgro, Kai Yi Mok, Xavier Didelot, Nicholas J. Croucher, Elita Jauneikaite, Theresa Lamagni, Colin S. Brown, Juliana Coelho*, Shiranee Sriskandan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The UK observed a marked increase in scarlet fever and invasive group A streptococcal infection in 2022 with severe outcomes in children and similar trends worldwide. Here we report lineage M1UK to be the dominant source of invasive infections in this upsurge. Compared with ancestral M1global strains, invasive M1UK strains exhibit reduced genomic diversity and fewer mutations in two-component regulator genes covRS. The emergence of M1UK is dated to 2008. Following a bottleneck coinciding with the COVID-19 pandemic, three emergent M1UK clades underwent rapid nationwide expansion, despite lack of detection in previous years. All M1UK isolates thus-far sequenced globally have a phylogenetic origin in the UK, with dispersal of the new clades in Europe. While waning immunity may promote streptococcal epidemics, the genetic features of M1UK point to a fitness advantage in pathogenicity, and a striking ability to persist through population bottlenecks.

Original languageEnglish
Article number3916
JournalNature Communications
Issue number1
Publication statusPublished - Dec 2024

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