Enterotoxins from Clostridium difficile; diarrhoeogenic potency and morphological effects in the rat intestine.

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.