SHARP INCREASE IN THE INCIDENCE AND SEVERITY OF INVASIVE STREPTOCOCCUS PYOGENES INFECTIONS IN CHILDREN AFTER THE COVID-19 PANDEMIC (2019-2023): A NATIONWIDE MULTICENTER STUDY.

Objectives: A global surge in pediatric invasive group A streptococcal infection (iGAS) was reported after autumn 2022. This study analyzed the epidemiology and severity of iGAS in Spain, comparing two periods; P1: pre-outbreak (January 2019-September 2022) versus P2: outbreak (October 2022-July 2023).

Methods: Children ≤16 years with iGAS enrolled in the Spanish PedGAS-net (2019-2023), were included. Bacterial isolates were analyzed for emm typing, antibiotic susceptibility, and whole genome sequencing. Multivariate analysis identified risk factors for PICU admission and mortality.

Results: 558 cases were included; 307 (55.1%) were male, with a median age of 43.9 months (IQR:19.3-84.1). There were significantly more iGAS in P2 (35.7 vs. 4.5 cases/month, p<0.001), with higher PICU admissions (51.3% vs. 30.8%, p<0.001). Pneumonia was the most common syndrome (32.3%), with pleural effusion in 58.3%. Of the 130 samples available for emm-typing, the most frequent were emm1 (56.1%) and emm12 (27.1%). 245 (43.9%) required PICU admission. Factors associated with PICU were streptococcal toxic shock syndrome (STSS), pneumonia, necrotizing fasciitis, acute kidney failure, and previous consultation before diagnosis. The emm1 (especially M1_UK) increased PICU risk. 11 children (2.0%) died. STSS, sepsis, and central nervous system infection were associated with mortality.

Conclusion: In Spain, pediatric iGAS cases sharply increased during 2022-2023, with a remarkable increase in severity. Epidemiological surveillance of iGAS remains crucial.