Changing trends in Streptococcus pyogenes bacteraemia in adults in the post-COVID era

Since 2022, an increasing number of invasive group A streptococcal (iGAS) infections have been reported, with increasing severity and lethality. We aimed to compare the frequency and characteristics of bacteraemic GAS infections in adults before and after the COVID-19 pandemic.

This was a retrospective observational study of adult patients with Streptococcus pyogenes bacteraemia in two periods, January 2017 to December 2019 and October 2022 to December 2023. Demographics, clinical presentation, antibiotic treatment, therapeutic response, complications and outcome were analysed.

Thirty-five patients with Streptococcus pyogenes bacteraemia in the 3-year pre-pandemic group were compared with 36 patients in the 15-month post-pandemic group. The median ages in the pre-pandemic and post-pandemic groups were 65 (IQR = 28) and 64.5 (IQR = 31) years, respectively. The proportions of males and females in the pre-pandemic group were 69% and 31%, respectively, compared with 33% and 67%, respectively, in the post-pandemic group. Skin and soft tissue infections occurred in 77% and 53%, respectively (p = 0.032). Rare manifestations, such as pneumonia and meningitis, were diagnosed in the post-pandemic group. Septic shock was significantly less common in the pre-pandemic group, with rates of 26% vs. 56% (p = 0.011). Treatment response was good in 74% of the pre-pandemic group compared to 58% of the post-pandemic group (p = 0.155). Lethality was not significantly higher in the post-pandemic group (26% vs. 33%, p = 0.482) but the number of deaths per year was more than three times higher in the post-pandemic group.

In the post-pandemic period, the frequency of bacteraemic GAS infections in adults increased significantly. A higher proportion of women, a decrease in the age of women and an increase in the age of men, rare clinical manifestations, poor response to therapy and increased severity and number of deaths were the new features of adult disease observed in the post-pandemic period.