High‐frequency intracellular infection and erythrogenic toxin A expression undergo phase variation in M1 group A streptococci

Abstract excerpt

A clonal variant of serotype M1 group A streptococcus, strain 90-131, disseminated to several continents, where it was associated with severe systemic infections and toxic shock. Although this strain harbours the speA gene and is efficiently internalized by human epithelial cells, clinical isolates often fail to express the erythrogenic toxin under laboratory growth conditions. Cultures of strain 90-131 were...