The chick embryo test agrees with the mouse bio-assay for assessment of the pathogenicity of Listeria species

Abstract

The pathogenicity of 20 strains of Listeria was determined with the mouse intravenous bio‐assay and the 10‐day chick embryo chorioallontoic membrane test. In the former, survival in the spleen was measured and in the latter, the LD100 and LD50. There was good correlation between the results of the two tests. Listeria monocytogenes strains that grow in the mouse spleen had an LD100 of < 125 organisms, while strains in which the numbers of organisms in the mouse spleen remain constant had an LD100 > 125 organisms. Listeria seeligeri, L. innocua, L. welshimeri, L. grayi and L. murrayi did not persist in the spleen and the numbers of organisms used did not kill chick embryos.