Enterotoxin

Overview
An enterotoxin is a protein toxin released by a micro-organism in the lower intestine. Enterotoxins are frequently cytotoxic and kill cells by altering the permeability of the epithelial cells of the intestinal wall. They are mostly pore forming toxins, secreted by bacteria, that assemble to form pores in cell membranes. This causes the cells to die.

The death of cells that form the barrier between the intestinal lumen and the surrounding tissue causes interstitial fluid, composed of water and electrolytes to leak into the intestinal tract, causing diarrhea.

Organisms secreting enterotoxins
Examples of organisms secreting enterotoxins are: Escherichia coli O157:H7, Clostridium perfringens, Vibrio cholerae, Staphylococcus aureus, Rotavirus and Yersinia enterocolitica. These toxins have A and B subunits. The A subunit is responsible for the loss of permeability of the intestinal endothelial cells. The B subunit acts as a syringe, injecting the A subunit into the cytoplasm.