Toxin responsible for staphyloccal toxic shock syndrome?
Ref: Ananthnaraycm R. Paniker CKJ. Textbook of Microbiology. 8th Edition. Hyderabad: Universities Press; 2009. Pg. 198-9.Explanation:Virulence factors of Staphylococcus aureusCoagulaseCoagulase is an enzyme which brings about clotting of human or rabbit plasma.It acts with a 'coagulase reacting factor (CRF) present in plasma, binding to prothrombin and converting fibrinogen to fibrin.Eight types of coagulase have been identified.It is secreted by all Staphylococcus aureus. It has no specific role in pathogenesis of toxic shock syndrome. a-hemolysinIt is most potent membrane-damaging toxin.Susceptible cells have a specific receptor for a- toxin which allows the toxin to bind causing small pores through which monovalent cations can pass.The mode of action of alpha hemolysin is likely by osmotic lysis.Panton Valentine toxin (Leucocidin)Leucocidin {also known as Panton-Valentine toxin after its discoverers) is a two-component toxin, like the gamma lysin. being composed of two components (S and F).It is capable of efficiently lysing white blood cells by causing pore formation in the cellular membranes that increase cation permeabilitySuperantigens (Enterotoxins and Toxic shock syndrome toxin)Enterotoxins, six antigenic types (named SE- A. B. C, D. E and G). It cause diarrhea and vomiting and are responsible for staphylococcal food poisoning.TSST-1 is expressed systemically and is the cause of toxic shock syndrome (TSS). TSST- 1 is responsible for 75% of TSS.Superantigens stimulate T cells non-specifically without normal antigenic recognitionUp to one in five T cells be activated, whereas only 1 in 10,000 are stimulated during a usual antigen presentation.Cytokines are released in large amounts, causing the symptoms of TSS.Superantigens bind directly to class li major histocompatibility complexes of antigen- presenting cells outside the conventional antigenbinding grove.
Superantigenic toxin
Alpha hemolysin
Panton valentine toxin
Coagulase
Staphylococci