Epidemiological and molecular characterization of an invasive group A streptococcus emm32.2 outbreak

Jennifer E. Cornick*, Anmol M. Kiran, Roberto Vivancos, Jon Van Aartsen, Jenny Clarke, Edward Bevan, Mansoor Alsahag, Maaike Alaearts, Laura Bricio Moreno, Howard F. Jenkinson, Angela H. Nobbs, James Anson, Aras Kadiolgu, Neil French, Dean B. Everett

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


An emm32.2 invasive group A streptococcus (iGAS) outbreak occurred in Liverpool from January 2010 to September 2012. This genotype had not previously been identified in Liverpool, but was responsible for 32% (14/44) of all iGAS cases reported during this time period. We performed a case-case comparison of emm32.2 iGAS cases with non-emm32.2 control iGAS cases identified in the Liverpool population over the same time period to assess patient risk factors for emm32.2 iGAS infection. The emm32.2 iGAS cases were confined to the adult population. We show that homelessness, intravenous drug use, and alcohol abuse predisposed patients to emm32.2 iGAS disease; however, no obvious epidemiological linkage between the patients with emm32.2 iGAS could be identified. Comparative whole-genome sequencing analysis of emm32.2 iGAS and non-emm32.2 control isolates was also performed to identify pathogen factors which might have driven the outbreak. We identified 19 genes, five of which had previously been implicated in virulence, which were present in all of the emm32.2 iGAS isolates but not present in any of the non-emm32.2 control isolates. We report that a novel emm32.2 genotype emerged in Liverpool in 2010 and identified a specific subset of genes, which could have allowed this novel emm32.2 genotype to persist in a disadvantaged population in the region over a 3-year period.

Original languageEnglish
Pages (from-to)1837-1846
Number of pages10
JournalJournal of Clinical Microbiology
Issue number6
Publication statusPublished - Jun 2017

Bibliographical note

Funding Information:
We thank Jonathan Folb at the Royal Liverpool University Hospital Microbiology Department and Richard Drew at the Alder Hey Children's hospital for providing the study isolates. We also thank Gavin Williams at the Infection Control teams of Liverpool Community Health NHS Trust, Rebecca Molineux and Anne Wright at the Royal Liverpool and Broadgreen University Hospital Trust, and Rita Huyton and Gill Marsh at the Cheshire and Merseyside Health Protection Team of Public Health England for their support with data collection from case notes and case interviews. All authors declare no conflicts of interest. This work was supported by funding from the National Institute for Health Research (NIHR) Health Protection Research Unit (HPRU) in Emerging and Zoonotic Infections and HPRU in Gastrointestinal Infections, University of Liverpool, to R.V. The views expressed herein are those of the authors and not necessarily those of the NHS, the NIHR, the Department of Health, or Public Health England.

Publisher Copyright:
© 2017 Cornick et al.


  • Accessory genome
  • Antibiotic resistance
  • Comparative genomics
  • Epidemiological data
  • Molecular epidemiology
  • Phylogeny
  • Streptococci
  • Streptococcus pyogenes
  • Virulence factors
  • Whole-genome sequencing
  • iGAS


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