Assessing the influence of the COVID-19 pandemic on the incidence, clinical presentation, and clindamycin resistance rates of Streptococcus pyogenes infections

: Streptococcus pyogenes (Group A Streptococcus, GAS) is a prevalent cause of community-acquired bacterial infections, with invasive GAS (iGAS) infections presenting severe morbimortality. Clindamycin is generally used based on its antitoxin effect. This study investigates changes in iGAS incidence, clinical presentation, outcomes, and clindamycin resistance in an adult cohort. : Retrospective analysis of S. pyogenes episodes from a tertiary adult hospital in Barcelona (Spain) between 2015 and 2023. Pre-pandemic period includes data from 2015 to 2019. Pandemic period, from 2020 to 2021 and post-pandemic period comprised from 2022 to the first semester of 2023. : The global incidence of GAS infections in the pre-pandemic and post-pandemic periods was 2.62 and 2.92 cases per 10.000 hospital admissions; whereas for iGAS cases was 1.85 and 2.34. However, a transient decrease was observed during pandemic period: 1.07 and 0.78 per 10.000 hospital admissions. There was a significant fall in both GAS and iGAS infections during the pandemic period compared with the pre-pandemic incidence (p<0.001 for GAS infections and p=0.001 for iGAS cases) and the post-pandemic incidence (p= 0.032 for GAS infections and p=0.037 for iGAS cases). The most common source of infection was SSTIs with 264 (54%) cases. SSTIs and cases of necrotizing fasciitis increased across pandemic. Clindamycin resistance occurred in 13.5% of isolations during pre-pandemic and 17.5% in post-pandemic period (p=0.05). : Our study revealed a temporary reduction in iGAS infections followed by resurgence in post-pandemic period. The observed rise in clindamycin resistance emphasizes the importance of monitoring local resistance patterns for tailored treatment.