Comparative analysis of streptococcal toxic shock syndrome caused by three β-hemolytic streptococcal species in Japan

OBJECTIVES: We aimed to compare the clinical features in patients with streptococcal toxic shock syndrome (STSS) caused by the three β-hemolytic streptococci (BHS): Streptococcus pyogenes, Streptococcus agalactiae, and Streptococcus dysgalactiae subsp. equisimilis (SDSE). METHODS: Overall, 301 adult patients with STSS with S. pyogenes (32.9%), S. agalactiae (17.6%), and SDSE (49.5%) in Japan were enrolled between 2016 and 2021. Data were analyzed to identify differences in clinical characteristics among the three BHS. Bacterial isolates were examined for emm or capsular typing. RESULTS: The incidence of STSS with S. pyogenes declined during the COVID-19 pandemic, but STSS with S. agalactiae and SDSE did not. Patients with SDSE were the oldest (median age, 81 years; interquartile range, 70-88 years) followed by those with S. agalactiae (76 years; 67-85 years) and S. pyogenes (66 years; 58-78 years). The case fatality rates (CFRs) of STSS caused by the three BHS were not significantly different, ranging from 48-59%; however, the CFR significantly increased with age in patients with SDSE (P <0.05). CONCLUSIONS: The characteristics of STSS differed among the three BHS. Clinicians should be aware of poor outcomes in patients with STSS, and provide appropriate treatment at an early stage.