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. 2023 Jul;29(7):887-890.
doi: 10.1016/j.cmi.2023.03.001. Epub 2023 Mar 15.

The ongoing Streptococcus pyogenes (Group A Streptococcus) outbreak in London, United Kingdom, in December 2022: a molecular epidemiology study

Adela Alcolea-Medina  1 , Luke B Snell  2 , Christopher Alder  3 , Themoula Charalampous  4 , Tom G S Williams  3 ; Synnovis Microbiology Laboratory Group  5 ; Mark K I Tan  3 , Noor Al-Yaakoubi  3 , Gul Humayun  3 , William Newsholme  6 , Simon Goldenberg  7 , Gaia Nebbia  3 , Stuart J D Neil  4 , Rahul Batra  3 , Jonathan D Edgeworth  8
Collaborators, Affiliations

The ongoing Streptococcus pyogenes (Group A Streptococcus) outbreak in London, United Kingdom, in December 2022: a molecular epidemiology study

Adela Alcolea-Medina et al. Clin Microbiol Infect. 2023 Jul.

Abstract

Objectives: Epidemiological and whole-genome sequencing analysis of an ongoing outbreak of Streptococcus pyogenes (Group A Streptococcus) in London (United Kingdom).

Methods: Prospective identification of Group A Streptococcus cases from a diagnostic laboratory serving central and south London between 27 November and 10 December 2022. Case notes were reviewed and isolates were retrieved. Case numbers were compared with the previous 5 years. Whole-genome sequencing was performed with long-read, nanopore technology for emm typing and identification of superantigen genes. Associations of pathogen-related factors with an invasive disease were assessed by single-variable and multi-variable logistic regression.

Results: Case numbers began increasing in October 2022 from a baseline of 2.0 cases per day, and in December 2022, the average daily case numbers reached 10.8 cases per day, four-fold the number usually seen in winter. A total of 113 cases were identified during the prospective study period. Three quarters (86/113, 76%) were paediatric cases, including 2 deaths. Of 113 cases, 11 (10%) were invasive. In total, 56 isolates were successfully sequenced, including 10 of 11 (91%) invasive isolates. The emm12 (33/56, 59%) and emm1 (9/56, 16%) types were predominant, with 7 of 9 (78%) emm1 isolates being from the M1uk clone. The majority of invasive isolates had superantigen genes spea (7/10, 70%) and spej (8/10, 80%), whereas, in non-invasive isolates, these superantigen genes were found less frequently (spea: 5/46, 11% and spej: 7/46, 15%). By multivariable analysis of pathogen-related factors, spea (OR 8.9, CI 1.4-57, p 0.020) and spej (OR 12, CI 1.8-78, p 0.011) were associated with invasive disease.

Conclusions: emm12 and emm1 types predominate in the ongoing outbreak, which mainly affects children. In this outbreak, the spea and spej superantigen genes are associated with the severity of presentation.

Keywords: Bacterial typing; Epidemiology; Group A Streptococcus; Streptococcus pyogenes; Whole-genome sequencing.

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Figures

Fig. 1
Fig. 1
Daily cases (14-day moving average) of laboratory-reported Group A Streptococcus isolation from clinical samples between 1 January 2017 and 31 January 2023.
See this image and copyright information in PMC

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