Toxic Shock Syndrome Caused by Streptococcus dysgalactiae Subspecies equisimilis: A Report of a Rare Pediatric Case

Streptococcal toxic shock syndrome (STSS) is a severe invasive infection that has a high mortality rate. It is mainly caused by <i>Streptococcus pyogenes</i>. Nevertheless, STSS is also known to be caused by a group G <i>Streptococcus</i> identified as <i>Streptococcus dysgalactiae</i> subsp. <i>equisimilis</i> (SDSE). Invasive SDSE infection predominantly occurs in elderly individuals but is extremely rare in children. Furthermore, reports on STSS caused by SDSE are limited; hence, the clinical aspects and type of invasive mature M protein (<i>emm</i>) gene involved are unknown. A five-year-old girl with Down syndrome, tracheomalacia, and laryngomalacia presented to the emergency department with generalized edema of her face and upper body. She had undergone a tracheostomy and was receiving home ventilation. On admission, she showed hypotension (64/22 mmHg) with impaired consciousness. Blood testing showed elevated levels of inflammatory markers. Blood culture revealed the presence of SDSE and she was consequently diagnosed with STSS. The patient responded well to treatment and was discharged three weeks after admission. The <i>emm</i> subtype of the isolated SDSE strain was <i>stC1400,</i> with mutations in <i>csrS</i> and streptolysin S regulatory RNA in group G <i>Streptococcus</i> (<i>srrG</i>) genes. In this article, we report a case of STSS in a child caused by the <i>stC1400</i>strainof SDSE.