The action of toxins A, B, and C from Clostridium difficile was studied in the 
small intestine and colon of rats. All three caused fluid accumulation in the 
small intestine, maximal secretion being induced by 1 micrograms of toxin A, 20 
micrograms of B, and 15 micrograms of C. Both toxins A and C caused shedding of 
epithelial cells from the villi without visible damage to crypt cells; toxin A 
caused further extensive necrosis and bleeding. Toxin B caused secretion without 
visible damage to the epithelial cells, though this activity was unstable and 
decreased significantly after one week of storage. In the colon, toxin A caused 
secretion and shedding of surface epithelial cells without damage to crypt 
cells, toxin C caused only a weak secretion, and toxin B had no effect at all. 
In terms of immunohistochemistry, it was found that toxin A bound to the 
enterocytes at the tips of the villi but not to goblet and crypt cells. The 
complex expression or interaction of the toxins produced by Cl difficile may 
explain the broad spectrum of disease (diarrhoea, colitis, and pseudomembranous 
colitis) associated with this micro-organism.