Studies on the Pathogenicity ofYersinia enterocolitica

Abstract Analysis of the pathogenicity of Yersinia enterocolitica was performed with an experimental model successfully produced in rabbits by intraduodenal inoculation with strains isolated from various sources. Pathogenic strains easily penetrated the epithelial linings of the intestinal mucous membrane into the target reticuloendothelial tissues of the intestine, such as the lamina propria and lymph follicles, where they multiplied within mononuclear cells and produced granuloma. Granuloma, in severe infections, underwent necrobiosis and sometimes progressed to ulceration accompanied by colony formation of the organisms. In mild infections, granulomatous lesions were localized in lymph follicles and never progressed to ulceration. Nonpathogenic strains were rapidly excreted without penetration of epithelial linings. Y. enterocolitica should be within the category of invasion type enteropathogenic bacteria such as Shigella and Salmonella . Pathogenic behavior of Y. enterocolitica is discussed in comparison with that of Shigella and Salmonella .