Invasive streptococcal disease is defined as an infection associated with group A Streptococcus pyogenes. Since the mid-1980s, there have been reports from around the world of an increase in the incidence, and associated morbidity and mortality. One of clinical presentations is group A streptococcal toxic shock syndrome, which is differentiated from other types of this disease by the occurrence of shock and multi-organ system failure early in the course of the infection. Another is necrotising fasciitis, characterized by extensive local necrosis of subcutaneous soft tissues and skin and the isolation of S. pyogenes from a normally sterile body site. The other is a group of infections characterized by the isolation of S. pyogenes from a normally sterile site in patients not meeting the criteria for streptococcal toxic shock syndrome or necrotising fasciitis. Recently, cases associated with group B, C and G Streptococcus have been reported but less frequent.
