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

The changing epidemiology of invasive group A Streptococcus infections in Israel during the COVID-19 pandemic – Concurrent emergence and expansion of emm74.0 and emm77.0 (#315)

Merav Ron 1 , Tal Brosh-Nissimov 2 3 , Shir Nasimian 1 , Ruti Yashar 1 , Rabeha Kawasmi 1 , Zinaida Korenman 4 , Lea Valinsky 1 , Ruth Yishai 4 , Maya Davidovich-Cohen 1 , Michal Savion 5 , Assaf Rokney 1
  1. Public Health Laboratories – (PHL-J), Public Health Services (PHS), Ministry of Health (MOH), Jerusalem, Israel
  2. Infectious Diseases Unit, Assuta Ashdod University Hospital, Ashdod, Israel
  3. Faculty of Health Sciences, Ben Gurion University in the Negev, Beer Sheba, Israel
  4. Department of Laboratories , Public Health Services (PHS) MOH, Jerusalem, Israel
  5. Tel-Aviv District Health Office, Ministry of Health, Tel Aviv, Israel

Background: Invasive group A streptococcal (iGAS) disease is notifiable in Israel and all isolates are analyzed at the Streptococcus national reference center.

Methods: During 2019-2021 a total of 1,696 iGAS isolates (blood-51.3%, wounds-29.4%) were assigned into 113 emm types. Emerging clusters were further analyzed for antimicrobial susceptibility and whole genome sequencing. Sequences were analyzed for phylogeny, resistance and virulence determinants.

Results: An initial reduction in total iGAS incidence was observed during the first year of the COVID-19 pandemic (Figure 1), followed by the emergence and expansion of two previously rare types: emm74.0, emm77.0 (Figure 2).

The yearly incidence of iGAS during 2019-2021 was 6.8, 5.3 and 6.2 cases/100,000. The predominant emm types were emm106.0 (N=147, 8.7%), emm1.0 (N=124, 7.3%), emm77.0 (N=110, 6.5%), emm81.2 (N=90, 5.3%) and emm89.0 (N=87, 5.1%).

During 2021, emm77.0 was the cause of 110 cases, (6.4%) and became the leading type, followed by emm74.0 (54 cases, 3.2%). WGS-based phylogeny confirmed clonality (≤3 and ≤2 allelic differences, respectively) among geographically dispersed cases. emm77.0 and emm74.0 cases were mostly male (69%, 83%) adults ≥18 years (93%, 93%). Investigation indicated risk factors for emm74.0 were drug use, and homelessness. Both types were resistant to tetracycline (tet(M)). The emm77.0 strains were additionally resistant to trimethoprim/sulfamethoxazole (dfrG). The Israeli emm74.0 ST-120 sequence was distinct compared to an ongoing Canadian ST-120 outbreak profile (111 allelic differences).

Conclusions: The simultaneous emergence of two resistant and previously rare lineages may reflect selective advantage following reduction of respiratory transmission of GAS.

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