Question

Describe how the mechanism of action two of the exotoxins of bacteria differs in the host epithelial cells. Including: Enterotoxigenic Escherichia coli, Shiga toxin of enterohemorraghic E. coli, C. difficile Toxin A and B, and Vibrio cholorae toxin.

Answer 1

E Coli.produces toxin which interfere with the lining of the intestine results in secretion of excessive fluid causing diarrhea.where as shiga toxin are potent cytotoxins act to inhibit protein synthesis within target cells mainly act on lining of blood vessels ,the vascular endothelium ,breakdown of the lining and thus occur hemorrhagic colitis(blood in diarrhea)

Clostridium difficile mediated by 2 exotoxins Toxin A and Toxin B these toxins disrupt the cytoskeleton structure and the target cell causing cell death act mainly on intestine whereas vibrio cholorae produces toxins which causes massive diarrhoea.Cholera toxin acts by activation of adenylate cyclase cAMP system present on membrane of intestine.The increased level of cAMP responsible for altered transport of Na and Cl.second one is also act through by releasing prostaglandin which harm to intestinal layer.

The difference is most of the bacterial toxin show their effect through involvement of ADP-ribosylating proteins where as other toxins involve guanylate cyclase system, protein kinase and calcium for their action.