[Toxic action of Listeria monocytogenes]

Two hoggets and 56 albino mice were used to study the effect of a water-extracted antigen of Listeria monocytogenes, strains 1,4b and St. r., through freezing, thawing, shaking, and filtrating (Seitz filter). A histologic examination was made of sections of the brain, lungs, heart, liver, spleen, and kidneys, stained with hematoxylin-eosin. Most characteristic of the toxic effect were the necrobiotic changes in the brain and viscera as well as the histiocytic infiltrations with the formation of granulomas. The extracted antigen could be inactivated at 60 degrees C. The mortality rate of mice infected with both the antigen and Listeria organisms was highest, and this showed that the toxic substance participates in the Listeria infection.