Comparison of pathogenic factors expressed by group A Streptococci isolated from patients with streptococcal toxic shock syndrome and scarlet fever

Streptococcal toxic shock syndrome (STSS) is an illness with high mortality . To obtain clues to understanding the pathogenesis of STSS, we investigate d the expression of several pathogenic factors in ten group A streptococcus (GAS) isolates from ten patients with STSS in Japan, in comparison with te n GAS isolates from children with scarlet fever. The ten scarlet fever-deri ved GAS isolates were equally low in lethality and anti-phagocytic activity in mice and in the production of streptolysin O (SLO), and equally high in production of superantigenic exotoxins (SAGTs) and cysteine proteinase. By comparison, the ten STSS-derived GAS isolates were heterogeneous in the ex pression of the above pathogenic factors, which ranged from low to high val ues. Most of the ten STSS-derived isolates were higher in lethality and ant i-phagocytic activity and production of SLO, and lower in the production of SAGTs and cysteine proteinase than the ten scarlet fever-derived isolates. The results suggest that the lethality and anti-phagocytic activity examin ed in mice and SLO may be involved mainly in the development of most of the ten STSS cases. (C) 1999 Academic Press.