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

Emergent Streptococcus pyogenes M1UK in invasive disease compared to carriage isolates in the Netherlands (#313)

Boas CL van der Putten 1 , Lidewij W Rümke 2 , Stefan MT Vestjens 2 , Wendy CM Bril-Keijzers 1 , Bart JM Vlaminckx 3 , Brechje de Gier 4 , Nina M van Sorge 1
  1. Netherlands Reference Laboratory for Bacterial Meningitis (NRLBM), Amsterdam UMC, Amsterdam, Netherlands
  2. Medical Microbiology, University Medical Center Utrecht, Utrecht, Netherlands
  3. Medical Microbiology and Immunology, St Antonius Hospital, Nieuwegein, Netherlands
  4. Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, Netherlands

Background

The toxicogenic M1UK lineage of Streptococcus pyogenes has recently been reported among patients with invasive and non-invasive disease in various countries. In the United Kingdom and the Netherlands, the M1UK lineage has become dominant among emm1 isolates from patients.  We aimed to determine when this lineage emerged and whether it already asymptomatically colonized individuals in the Netherlands between 2009-2019.

Methods

We selected 52 S. pyogenes emm1 isolates from the Netherlands, of which 35 were isolated from the nasopharyngeal tract of carriers and 17 from patients with invasive S. pyogenes disease. Isolates were whole-genome sequenced using Illumina technology and analysed using an open-source pipeline of the Netherlands Reference Laboratory for Bacterial Meningitis (https://github.com/NRLBM/assembly).

Results

Ten out-of-52 emm1 isolates (19%) were identified as M1UK based on presence of 27 lineage-defining SNPs. Of the 10 M1UK isolates, 8 (80%) were obtained from patients with invasive disease, whereas only 9 out-of-42 (21%) M1global isolates were considered invasive. Although rare, M1UK was also found among carriers. The earliest M1UK isolate in our dataset was from 2016.

Discussion

M1UK was identified among asymptomatic carriers although this was very rare. We did not identify M1UK strains prior to the first reported M1UK in the UK. M1UK seems to be even more associated with invasive disease than M1global strains although more data is needed to perform a well-powered statistical analysis. Further sequencing, genomic characterisation and time-stratified analysis is underway.