Divergent effects of types 1 and 12 on invasive group A streptococcal infections-results of a retrospective cohort study, Germany 2023.

As a potential side effect of the severe acute respiratory syndrome coronavirus type 2 pandemic, invasive group A (iGAS) infections in Europe have increased dramatically in both children and adults in the end of 2022. This epidemiological and molecular study describes the distributions of streptococcal genes encoding the M antigen ( types) and superantigens in patients with invasive and non-invasive GAS infections. From December 2022 to December 2023, a total of 163 GAS isolates were collected from sterile and non-sterile sites of patients at five hospitals in Germany including two tertiary care centers. Genes encoding M protein and superantigens were determined following the guidelines of CDC Streptococcus laboratory. Patients' characteristics were reviewed retrospectively. Correlations of clinical factors, types, and superantigens with rates of invasive infections were analyzed. Of the 163 included GAS cases, 112 (69%) were considered as invasive. In total, 33 different types were observed, of which ( = 49; 30%), ( = 15; 9%), and ( = 14; 9%) were most prevalent. In total, 70% of isolates belonged to M1 lineage. No difference in invasive infections was observed for the M1 lineage compared with other isolates. However, the type, presence of , , or , as well as adulthood were significantly associated with invasive infections. In contrast, isolates were significantly less associated with invasive infections. Multivariable analysis confirmed a significant influence of and adulthood on iGAS infections. This study underlines the importance of continuous monitoring of genomic trends and identification of emerging GAS variants. This may aid in delineating pathogenicity factors of that propel invasive infections.