J E Wolf, L G Rabinowitz

After decades marked by a decrease in the incidence and severity of scarlet fever and streptococcal soft-tissue infections, invasive infections with group A streptococci have reemerged as a global public health problem. Sporadic outbreaks of a rapidly progressive disorder characterized by fever, shock, desquamating rash, and multiorgan system failure often associated with severe suppurative soft-tissue infection have recently been recognized in young, otherwise-healthy adults. Referred to as streptococcal toxic shock-like syndrome, this acute, progressive, often fatal illness appears to be related to an overall change in the virulence of group A streptococci and the reappearance of highly mucoid exotoxin-producing strains. However, the relationship between virulence factors, epidemiological features, and precise pathogenesis of these infections remains unclear. The 80% incidence of soft-tissue involvement in streptococcal toxic shock-like syndrome and the high frequency of progression to necrotizing fasciitis, myositis, or even death are unprecedented. The type and extent of tissue injury, systemic toxicity, and multiorgan system failure associated with this syndrome appear to be mediated by streptococcal pyrogenic exotoxins via the induction of biologically potent endogenous cytokines. The observed increase in the incidence and severity of invasive group A streptococcal infections coincides with the resurgence of genetically related, highly virulent strains of Staphylococcus pyogenes that express an invasive phenotype and carry a specific gene for pyrogenic exotoxin A. The changing spectrum of invasive group A streptococcal infections has prompted a reexamination of the microorganism and its diverse clinical manifestations. A clonal basis for increased virulence expression is supported epidemiologically. As the incidence of streptococcal toxic shock-like syndrome appears to be increasing, it is imperative that clinicians become familiar with the presentation of this syndrome so they can diagnose and treat it in a timely and effective manner.