A case of streptococcal toxic shock syndrome due to Group G streptococci identified as Streptococcus dysgalactiae subsp. equisimilis

A 79-year-old man with a 3-month history of lymphedema of the lower limbs, and diabetes mellitus, was admitted to our hospital for suspected deep venous thrombosis. Several hours after admission, leg pain and purpura-like skin color appeared. On the 2nd hospital day, he was referred to our department for possible acute occlusive peripheral artery disease (PAD) and skin necrosis with blisters; however, computed tomography with contrast showed no occlusive lesions. He had already developed shock and necrotizing deep soft-tissue infections of the left lower leg. Laboratory findings revealed renal dysfunction and coagulation system collapse. Soon after PAD was ruled out, clinical findings suggested necrotizing deep soft-tissue infections, shock state, disseminated intravascular coagulation, and multiple organ failure. These symptoms led to a high suspicion of the well-recognized streptococcal toxic shock syndrome (STSS). With a high suspicion of STSS, we detected Group G β-hemolytic streptococci (GGS) from samples aspirated from the leg bullae, and the species was identified as Streptococcus dysgalactiae subsp. equisimilis (SDSE) by 16S-ribosomal RNA sequencing. However, unfortunately, surgical debridement was impossible due to the broad area of skin change. Despite adequate antimicrobial therapy and intensive care, the patient died on the 3rd hospital day. The M-protein gene (emm) typing of the isolated SDSE was revealed to be stG6792. This type of SDSE is the most frequent cause of STSS due to GGS in Japan. We consider it to be crucial to rapidly distinguish STSS from acute occlusive PAD to achieve life-saving interventions in patients with severe soft-tissue infections.