Invasive Group A Strep (GAS) infection refers to infection in the setting of culture isolation of GAS from a normally sterile site (i.e. blood, pleural fluid, joint fluid, CSF)
Case fatality rate for invasive infection is 30-45%
occurs in up to 50% of necrotizing soft tissue infections
early onset (within hours) of hypotension, tachycardia, organ failure
fever or hypothermia, altered mental status
soft tissue findings (severe pain at site of minor trauma, localized swelling and erythema, ecchymosis, skin sloughing) progress to deep infection within 24-72 hrs
TSS is not always due to Grp A Strep; other pathogens include Staphylococci, and other Strep including Group B