Pyrogenic toxin superantigen site specificity in toxic shock syndrome and food poisoning in animals

Staphyloccus aureus and Streptococcus pyogenes express pyrogenic toxin supe rantigens (PTSAgs) that are associated with toxic shock syndrome (TSS) and staphylococcal food poisoning (SFP). Most PTSAgs cause TSS in deep-tissue i nfections, whereas only TSS toxin 1 (TSST-1) is associated with menstrual, vaginal TSS. In contrast, SFP has been linked only with staphylococcal ente rotoxins (SEs). Because of the differential abilities of PTSAgs to cause sy stemic or localized symptoms in a site-dependent manner, the present study was undertaken to assess the toxins' abilities to cross mucosal barriers. T he activity of three PTSAgs when delivered orally, vaginally, or intravenou sly to rabbits and orally to monkeys was investigated. TSST-1 induced shock via all three routes in rabbits. Although active when administered intrave nously, SEC1 and streptococcal pyrogenic exotoxin A (SPEA) did not cause sy mptoms when administered orally or vaginally. Only SEC1 induced emesis in t he monkey feeding assay. TSST-1, albeit less stable than SEC1 and SPEA to p epsin. induced diarrhea in monkeys. Our results may explain the unique asso ciation of TSST-1 with menstrual TSS and why SPEA is only rarely associated with TSS after pharyngitis, despite being highly associated with TSS after subcutaneous infections. Finally, our studies indicate that enterotoxicity in SFP is not the result of superantigenicity.