EXPERIMENTAL-INFECTION OF AXENIC MICE BY YERSINIA-ENTEROCOLITICA

Abstract

Although most of Y. enterocolitica strains isolated from man have no pathogenicity for laboratory animals, some strains are pathogenic for conventional mice and most strains are probably pathogenic for nude mice. Infection of germ-free mice with a strain of Y. enterocolitica non pathogenic for holoxenic mice was studied. C3H/He mice are apparently sensitive to the infection by gavage or aerogenic and peritoneal routes. They all die 8-12 days after injection of an inoculum of 5 .times. 105 viable cells. Germ-free NCS mice were also sensitive to oral and aerogenic infection but not to the peritoneal infection; the difference between C3H/He and NCS peritoneal sensitivity may be due to more bactericidal activity of the peritoneal phagocytes of the latter. C3H/He and NCS holoxenic control mice infected with the same inoculum of the same strain, did not show any symptoms, and all attempts to isolate Y. enterocolitica failed 3 mo. after the challenge. Germ-free mice killed by the infection showed histopathological findings, i.e., abscesses involving intestinal wall, liver and spleen; they were similar to those described in experiments with pathogenic strains for conventional mice (holoxenic) and to those observed in infection of athymic nude mice with strains non pathogenic for conventional mice. This infectious disease model is discussed with regard to natural human infection.