Gram-negative endotoxins and staphylococcal toxic shock syndrome

Strains of Staphylococcus aureus isolated from toxic shock syndrome (TSS) produce toxic shock syndrome toxin 1 (TSST1) which causes a shock-like illness in rabbits with many features similar to TSS in humans. TSST1 is lethal per se in rabbits and also acts synergistically with endotoxin to potentiate lethality. The mode of action of TSST1 is as yet unknown; it has been suggested that it may act by inhibiting the reticuloendothelial system thus allowing endotoxic shock to occur. Rabbits pretreated with polymyxin-B, which prevents the effect of endotoxin, were found to be protected from death by TSST1 indicating that endotoxin is indeed implicated in the pathogenesis of TSS. Specific pathogen-free rabbits which presumably have negligible levels of circulating LPS were susceptible to TSST1 suggesting that very small amounts of endotoxin are sufficient to potentiate lethality. The ways in which TSST1 may allow shock to occur is discussed.