Non-necrotizing soft tissue infection and streptococcal toxic shock syndrome caused by a novel Streptococcus pyogenes subtype (emm76.10)

Abstract

We report a case of non-necrotizing soft tissue infection and streptococcal toxic shock syndrome (STSS) caused by a new emm subtype (emm76.10) of group A Streptococcus pyogenes (GAS). A 54-year-old Japanese woman suffering from fever, fatigue, and lower abdominal pain with erythema for 3 days was admitted to our hospital. She also had hypotension and multiple organ failure. Due to the presence of STSS and examination of necrotizing soft tissue infection from her lower abdomen to left thigh, exploratory incision was performed. Tissue cultures from exudates and fascia yielded positive results for GAS growth, although blood cultures were negative. After 15 days of antimicrobial therapy, she fully recovered without any complications. Genotyping of this isolate indicated a novel emm subtype (emm76.10), with five amino acid substitutions in the emm76.0 subtype sequence and a long sequence of 780 bp. This isolate was resistant to tetracyclines, macrolides lincosamides, and fluoroquinolones, owing to the presence of antibiotic-resistance determinants tet(M) and erm(B) and point mutations, Ser79Phe/Ser81Phe, in quinolone resistance-determining regions of parC/gyrA. In conclusion, our observations suggested the importance of early-stage exploratory incision and drainage from the infected region for the isolation and characterization of causative bacteria to select appropriate antibiotics for treatment.