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Published on: December 7, 2021
Evidence for early circulation of the M1UK sublineage of Streptococcus pyogenes in Germany, 2015-2023
Susann Rößler1, Sébastien Boutin2,3,4, Reinhard Berner5
1Institute for Medical Microbiology and Virology, University Hospital Carl Gustav Carus Dresden, Technische Universität Dresden, Dresden, Germany.
Background:
Several European countries have reported a rise in invasive Group A Streptococcus (GAS) infections, particularly linked to the toxigenic emm1 sublineage M1UK. In Germany, historical molecular data are limited due to the absence of systematic molecular surveillance.
Methods:
We performed whole-genome sequencing (WGS) on 189 invasive Streptococcus pyogenes isolates collected between January 1, 2015, and May 31, 2023, at University Medical Center Carl Gustav Carus, TU Dresden. Clinical data were extracted from patient records. M1UK sublineage identification was based on 27 characteristic single nucleotide polymorphisms (SNPs). A Bayesian coalescent analysis estimated the evolutionary timescales of the M1UK clade in Germany.
Results:
The most common emm type was emm1 (34%, 64/189), followed by emm12, emm4, and emm89. Of the 64 emm1 isolates, 31 (48%) were M1UK. No significant associations were found between clinical outcomes and M1UK or M1global genotypes. Although a post-pandemic shift favouring M1UK was observed, our analysis indicates that M1UK had already been circulating in Germany by 2017. The estimated most recent common ancestor dates to 2012 (95% highest posterior density: 2009-2015), with a stable effective population size over time.
Conclusion:
Our findings confirm the pre-pandemic circulation of M1UK in Germany. While the clinical impact of M1UK remains unclear, integrating clinical data with high-resolution molecular surveillance may improve early detection of emerging high-risk clones.
Insights
Invasive Group A Streptococcus (GAS) infections, particularly the M1UK strain, were circulating in Germany before the pandemic. Molecular surveillance is key to detecting high-risk bacterial clones.
Area of Science:
- Microbiology
- Epidemiology
- Genomics
Background:
- Several European nations report increased invasive Group A Streptococcus (GAS) infections, with the toxigenic emm1 sublineage M1UK being a notable driver.
- Germany lacks comprehensive historical molecular data on GAS due to absent systematic surveillance.
Purpose of the Study:
- To investigate the molecular epidemiology and evolutionary history of invasive Streptococcus pyogenes in Germany.
- To identify the prevalence of the M1UK sublineage and its circulation timeline.
Main Methods:
- Whole-genome sequencing (WGS) of 189 invasive Streptococcus pyogenes isolates (2015-2023).
- Identification of the M1UK sublineage using 27 characteristic single nucleotide polymorphisms (SNPs).
- Bayesian coalescent analysis to estimate evolutionary timescales.
Main Results:
- The emm1 type was most prevalent (34%), with 48% of these isolates belonging to the M1UK sublineage.
- M1UK was circulating in Germany by 2017, with an estimated common ancestor in 2012.
- No significant clinical outcome differences were observed between M1UK and M1global genotypes.
Conclusions:
- Confirms pre-pandemic circulation of the M1UK GAS strain in Germany.
- Highlights the need for integrated clinical and molecular surveillance for early detection of emerging high-risk bacterial clones.
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