[Contributions to the strain-specific virulence of Cryptococcus neoformans. Animal experiments with two C. neoformans-strains isolated from bird manure. Preliminary report (author's transl)]

Abstract

The results briefly presented here highlight some of the observations met with during the course of a study aimed at finding out differential pathogenic behavior of the two strains of Cryptococcus neoformans i.e. W71/A117 and W2/A94 with special reference to cryptococcoma formation. Both strains were isolated from bird excreta but differed in their gross and microscopic morphology. Groups of male albino mice NMRI were separately inoculated, intramuscularly, with a comparable dose of the two strains. All the 50 animals challenged with W71/A117 developed macroscopically distinct cryptococcoma of variable size, and fatally progressive disease, involving most of the internal organs, namely, brain, heart, lung, liver, spleen and kidneys. On the contrary, only 34 of the 50 mice infected with the strain W2/A94 showed cryptococcoma formation at the site of inoculation, which were comparatively much smaller in size and gradually diminished. None of the animals, observed over a period of 93 days, died, and showed any sign of metastasis. In another series of experiment, only one instance of mortality was observed in a group of 80 mice inoculated intraperitoneally with about 2 X 10(7) viable cells of this strain. However, the fungus could be recovered, in a majority of cases, only from the brain of animals sacrificed after one month, though most of them showed no sign of sickness. The number of mice yielding positive cultures gradually decreased, and after 87 days the fungus could not be isolated from any organ. The high morbidity and mortality in mice caused by strains W71/A117 was significantly lowered when the animals were infected intramuscularly 3 months ago with the strain W2/A94. After an observation period of 61 days, 91% of the double infected animals were still alive in comparison to 23% survival among the animals challenged with the strain W71/A117 only.