F2F Poster 21st Lancefield International Symposium for Streptococci and Streptococcal Diseases 2022

Population Structure of an Emergent Group A Streptococcus M1UK Clone in Canada (#318)

Walter Demczuk 1 , Irene Martin 1 , Linda Hoang 2 , Marc-Christian Domingo 3 , Allison McGeer 4 , Gregory J Tyrrell 5 , Julianne Kus 6 , Jessica Minion 7 , Paul Van Caeseele 8 , Rita Raafat Gad 9 , David Haldane 10 , George Zahariadis 11 , Lori Strudwick 12 , Kristen Mead 13 , Laura Steven 14 , Michael R Mulvey 1
  1. Public Health Agency of Canada, Winnipeg, MANITOBA, Canada
  2. British Columbia Centre for Disease Control, Vancouver, British Columbia, Canada
  3. Laboratoire de santé publique du Québec, Ste-Anne-de-Bellevue, Quebec, Canada
  4. Department of Microbiology, Mount Sinai Hospital, Toronto Invasive Bacterial Diseases Network (TIBDN), Toronto, Ontario, Canada
  5. The Provincial Laboratory for Public Health (Microbiology), Edmonton, Alberta, Canada
  6. Public Health Ontario, Toronto, Ontario, Canada
  7. Roy Romanow Provincial Laboratory, Regina, Saskatchewan, Canada
  8. Cadham Provincial Laboratory, Winnipeg, Manitoba, Canada
  9. Office of the Chief Medical Officer of Health, New Brunswick Department of Health, Fredericton, New Brunswick, Canada
  10. Queen Elizabeth II Health Science Centre, Halifax, Nova Scotia, Canada
  11. Newfoundland Public Health Laboratory, St. John's, Newfoundland and Labrador, Canada
  12. Yukon Communicable Disease Control, Whitehourse, Yukon, Canada
  13. Queen Elizabeth Hospital, Charlottetown, Charlottetown, Prince Edward Island, Canada
  14. Stanton Territorial Hospital Laboratory, Yellowknife, Northwest Territories, Canada

Background: The emergence of a novel group A Streptococcus (GAS) emm1 lineage (M1UK) in the United Kingdom was associated with invasive and non-invasive disease. The clone is characterised by 27 key genomic single-nucleotide variations (SNVs) and overproduction of SpeA. M1UK was first observed in the UK during 2010 and by 2016 represented 84% of all emm1 strains. M1UK has been broadly disseminated internationally including Canada, USA and the Netherlands. Phylogenetic analysis was conducted to characterize the international dissemination and population structure of the M1UK clone.

Methods: Core SNV phylogenetic analysis was conducted on GAS isolates collected in Canada from 1993 to 2020 (n=1494), the Netherlands in 2019 (n=44), the UK from 2009 to 2016 (n=135), and the USA from 2013 to 2019 (n=12). M1UK genotypes were determined by mapping sequencing reads against reference strain MGAS5005 and identifying 27 characteristic genomic SNVs.  Molecular factors were identified from genome assemblies using custom molecular typing pipelines.

Results: The first M1UK isolates in Canada were observed in 2015 (n=3) and increased to represent 33% (n=138) of emm1 isolates sequenced in 2019.  Phylogenetic analysis of the 1685 emm1 isolates indicated the international M1UK strains (n=431) were closely genetically related, differing by an average of 16 SNVs.   Clustering was observed among the M1UK strains on a country basis and regionally within Canada.

Conclusions: Whole genome sequence comparisons of M1UK isolates between four countries show a highly clonal distribution. This highlights the need for international comparisons to monitor the dissemination of emergent clones to provide a rapid response and support for public health interventions and vaccine development.