R.A Ataei - Instructor
GH Behzadian nejhad - Associate professor

clostridium difficile has been recognized as the major cause of pseudomembranous colitis.this bacterium produces two toxins(an enterotoxin -cytotoxin and a potent cytotoxin called toxin A and toxin B erespectively).these toxins have implicated in pathogenesis of the disease.however,histopathological effects of their molecular mass less than ۱۰۰KDa have been essayed.in the persent study,we examined the dose repsonse and time course of these toxins in ligated rebbit ileal loop and cell culture link BK (boving kidney).the ۱-۱۰ mg/ml toxin A, with molecullar weight of ۲۵ KDa,in ligated rabbit ileal loop(۶ rabbits with maximum of ۱۵ loopes in each animals) showed a series of histopathological changes leading to inflammation,fluid or bloody fluid accumulation,mucous and villi disraotion in lammina properia.different concentration of toxin B(MW=۶۰ KDa) had no effect on fluid accumulation in striped rabbit ileal loop but caused driness and necrosis intensively.cultured cells exposed to ۱mg/ml toxin B showed a series of cytopathologic changes  leading to cell retraction and rounding accompanied by the marginalization of the cell membrane.Enhancement of toxin concentration caused increament of cytopathic effects.

clostridium difficile, pseudomembranouse coltitis, Toxin Aand B, rabbit ligated ileal loop, cell culture