[Current views on the pathomorphology and pathogenesis of dysentery]

According to the literature and the authors' data in patients who died of dysentery Shigellae are found seldom because of postmortem shedding of superficial colonic epithelium infected by them. Shigella adhesion and invasion into the colonocytes are regularly found in the colon biopsies. As shown recently in experiments, Shigella outer membrane proteins forming "contact haemolysin" ("virulence plasmid" product) are responsible for their invasion. In the small intestine this cytotoxin is destroyed by trypsin, therefore Shigella invasion takes place in the large intestine where it also lyses vacuole membranes around the bacteria in colonocytes. Widespread cytopathic alterations of the epithelium with a damage to ribosome and protein synthesis, disturbance of vascular permeability and fluid hypersecretion in the small intestine result from Shiga-like enterotoxin-cytotoxin. Extent of the inflammatory leukocyte response depends on the degree of Shigella invasion and multiplication and the destruction of the epithelium. Damages to the endothelium and blood coagulation system resulting occasionally in the infectious-toxic shock, are associated with Shigella destruction by leukocytes and absorption of lipopolysaccharide endotoxin released by them. Interepithelial lymphocytes especially those containing lysosome-like granules (similar to the blood "natural killers") play an important role in the response to Shigella.