Clinical aspects of invasive infections with Streptococcus dysgalactiae ssp. equisimilis in Japan: differences with respect to Streptococcus pyogenes and Streptococcus agalactiae infections

Area of Science:

• Infectious Diseases
• Microbiology
• Epidemiology

Background:

• Streptococcus dysgalactiae ssp. equisimilis (SDSE) is an emerging pathogen causing invasive and non-invasive infections.
• Comparison of invasive SDSE infections with Streptococcus pyogenes (GAS) and Streptococcus agalactiae (GBS) is crucial for understanding disease burden and clinical management.

Purpose of the Study:

• To compare the clinical features of invasive SDSE infections with those of GAS and GBS.
• To identify risk factors and indicators associated with poor outcomes in invasive SDSE infections.

Main Methods:

• Active surveillance of invasive SDSE, GAS, and GBS infections across 142 Japanese medical institutions over one year.
• Collection and microbiological characterization of isolates, alongside clinical data from 231 SDSE, 97 GAS, and 151 GBS cases.
• Statistical analysis to determine associations between clinical factors, emm types, and patient outcomes.

Main Results:

• Invasive SDSE infections predominantly affected elderly patients (median age 75 years) with underlying conditions (79%).
• Poor outcomes (death or sequelae) occurred in 18% of SDSE patients, with low white blood cell counts and thrombocytopenia being significant risk factors.
• The stG6792 emm type was associated with a significantly higher risk of poor outcome (OR 2.4).

Conclusions:

• Invasive SDSE infections present distinct clinical features compared to GBS, often affecting older individuals.
• Primary care physicians should consider SDSE in elderly patients presenting with severe infections.
• Prompt recognition of clinical indicators and specific bacterial types can aid in managing invasive streptococcal infections.