Clinical isolates of Shigella species induce apoptosis in macrophages.

Shigella species are invasive enterobacteria that cause dysentery, a severe form of diarrhea. The ability to invade epithelial cells and to kill macrophages is essential for virulence in a prototype Shigella flexneri strain. It is shown here that clinical isolates of both S. flexneri and Shigella sonnei invade epithelial cells and are cytotoxic to macrophages in vitro. Furthermore, clinical Shigella strains kill macrophages by inducing apoptosis. The conservation of the ability to induce macrophage apoptosis by clinical isolates suggests that this function plays a crucial role in the pathogenesis of Shigella species.