Shigellosis Due to Shigella dysenteriae 1: Relative Importance of Mucosal Invasion versus Toxin Production in Pathogenesis

Abstract

The disease-provoking capacity of a wild-type strain of Shigella dysenteriae 1 capable both of penetrating intestinal epithelial cells and of producing toxin was compared with that of three mutants derived from it that were altered in both or either of these cell properties. The results of studies on several models in animals (the ileal loop in rabbits and starved guinea pigs and monkeys) indicate that the disease caused by a nontoxigenic, penetrating mutant was not easily distinguishable from that of the original toxin-producing parent strain. A nonpenetrating mutant that had retained the ability to produce toxin and a double mutant that lacked ability to penetrate and produce toxin did not cause clinical disease. These findings do not exclude a function for toxin in the pathogenesis of dysentery by S. dysenteriae but indicate that the ability to penetrate and multiply in the colonic mucosa is more important in causing disease.