Involvement of streptococcal superantigens in streptococcal toxic shock syndrome

We report a non-fatal case of streptococcal toxic shock syndrome (STSS), caused by a Streptococcus pyogenes emm118 strain encoding a novel variant of streptococcal mitogenic exotoxin Z (SMEZ-34). This variant was responsible for the major mitogenic activity in the cell culture supernatant. Patient sera showed seroconversion towards SMEZ implicating a role for this toxin in STSS.