POUVOIR PATHOGENE EXPERIMENTAL DE YERSINIA ENTEROCOLITICA CHEZ LA SOURIS ATHYMIQUE (NUDE)

Out of the 4,500 strains of the authors' collection of Yersinia enterocolitica, usually non pathogenic for laboratory animals, 5 or 6 strains appeared to be naturally pathogenic for mice. Using these strains and non pathogenic strains representing more than 90% of human isolates in the world (biotype 4, serotype 0:3, phagocyte VIII; biotype 2, serotype 0:9, phagotype X₃), the pathogenicity for cyclophosphamide treated mice and athymic Nude mice has been tested. Highly pathogenic strains killed conventional as well as cyclophosphamide treated mice. Non pathogenic strains for conventional mice did not show any pathogenicity for cyclophosphamide treated mice (strain IP161 excepted) but killed 30 athymic Nude mice inoculated 5 X 10⁸ and 5 X 10⁵ organisms by the oral or intraperitoneal routes. Nude mice infected intragastrically or intraperitoneally showed signs of enteritis and bronchopneumonia followed by a septicemia. Abscesses were found in the liver, spleen and ileal wall. The infection of Nude mice with Y. enterocolitica resembles naturally acquired human infection where 2/3 of the cases are enteritis among under 4 yr old children and where septicemia occurs among immunologically deficient adults. The role of T lymphocytes and of immune functions in Y. enterocolitica infection is discussed through this model.