Pathophysiology
In both TSS (caused by S. aureus) and TSLS (caused by S. pyogenes), disease progression stems from a superantigen toxin that allows the nonspecific binding of MHC II with T cell receptors, resulting in polyclonal T cell activation. In typical T cell recognition, an antigen is taken up by an antigen-presenting cell, processed, expressed on the cell surface in complex with class II major histocompatibility complex (MHC) in a groove formed by the alpha and beta chains of class II MHC, and recognized by an antigen-specific T cell receptor.
By contrast, superantigens do not require processing by antigen-presenting cells but instead interact directly with the invariant region of the class II MHC molecule. In patients with TSS, up to 20% of the body's T cells can be activated at one time. This polyclonal T-cell population causes a cytokine storm, followed by a multisystem disease. The toxin in S. aureus infections is TSS Toxin-1, or TSST-1. The TSST-1 is secreted as a single polypeptide chain.
The gene encoding toxic shock syndrome toxin is carried by a mobile genetic element of S. aureus in the SaPI family of pathogenicity islands.
Read more about this topic: Toxic Shock Syndrome