INFECTION OF WHITE SWISS MICE WITH AIRBORNE CRYPTOCOCCUS NEOFORMANS

Smith, C. D. (Communicable Disease Center, Kansas City, Kansas), R. Ritter, H. W. Larsh, and M. L. Furcolow. Infection of white Swiss mice with airborne Cryptococcus neoformans. J. Bacteriol. 87:1364–1368. 1964.—A group of 39 white Swiss male mice were allowed to run 3 days on previously sterilized soil that had been seeded with Cryptococcus neoformans 1 year previously. It was determined that the soil contained an average of 1.6 × 106 viable yeast cells per ml. The mice were observed for 24 weeks, at which time the survivors were necropsied. The total mortality rate during this period was 44%; 67% of the mice had positive cultures, including all who had a fatal infection. Two additional experiments were done with the same strain with the use of aerosols produced by a Henderson apparatus. In experiment 1, 39 mice received 11,000 viable cells each; in experiment 2, 40 mice received 14,622 viable cells. Both groups of mice showed similar mortality rates, with a total of 77% dead after 20 weeks in experiment 1, and 80% in experiment 2. All of the mice in experiment 1 had positive cultures, as did 95% of the mice in experiment 2.