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

Clinical and molecular epidemiology of group A streptococcal carriage and invasive disease in the Netherlands, 2009-2019 (#320)

Lidewij W. Rümke 1 , Stefan M.T. Vestjens 1 , Brechje de Gier 2 , Wendy C.M. Bril-Keijzers 3 , Boas C.L. van der Putten 3 , Nina M. van Sorge 3 , Bart J.M. Vlaminckx 4
  1. Medical Microbiology, University Medical Center Utrecht, Utrecht, the Netherlands
  2. RIVM, Bilthoven, the Netherlands
  3. The Netherlands Reference Laboratory for Bacterial Meningitis AUMC, Amsterdam, the Netherlands
  4. Medical Microbiology & Immunology, St. Antonius hospital, Nieuwegein, the Netherlands

Background
Recent surges in invasive Group A Streptococcal (iGAS) infections in the Netherlands highlight the need to provide updated information on circulating emm-types and associated disease presentations to raise awareness and inform public health decision making.

Methods
Isolates from iGAS patients with bacteremia (n=264) and asymptomatic nasopharyngeal GAS carriers (n=304) were retrospectively collected over the period 2009-2019. All isolates were emm-typed through Sanger sequencing.

Results
Predominant emm-types among iGAS isolates were emm1 (30%), emm3 (13%), emm89 (10%), emm28 (8%), and emm75 (6%), with a remarkable decline of emm3 throughout the study period with 24/106 (24%) isolates in 2009-2014 compared to 9/158 (6%) isolates in 2015-2019 (Fisher’s exact p<.0001). Among iGAS cases, the case fatality rate was 17%. Clinical iGAS syndromes included skin/soft tissue infection (31%), bacteremia without focus (19%), respiratory tract (13%), necrotizing soft tissue (9%), bone/joint (8%), and pregnancy-associated infection (6%). Thirty-six patients (14%) developed streptococcal toxic shock syndrome (STSS). Emm1 and emm3 caused the majority of necrotizing soft tissue infections (18/23, 78%), STSS (23/36, 64%), intensive care admittance (55/84, 65%) and death (22/45, 49%). Interestingly, these dominant emm-types were only observed with low frequencies among carriers (Figure 1).

Conclusions
Dominant emm-types in Dutch iGAS and carriage isolates only partially overlapped, suggesting specific emm-types are more prone to cause invasive disease. A significant decline of emm3 prevalence in iGAS was seen over the period 2009-2019. Emm1 and emm3 were the most prevalent emm-types among invasive isolates and represented the majority of necrotizing soft tissue infections, STSS and fatal cases.

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