The pathogenicity of the purified hyphae of Filobasidiella neoformans was determined. The hyphal particles were inoculated into white Swiss female mice via the intracranial and intravenous route. Upon autopsy, infection was seen with as few as 25 hyphal elements. The brain, liver, and spleen were examined culturally and the brain examined histologically to prove the pathogenicity of the purified hyphae.

Interactions between macrophages (alveolar and peritoneal) from normal, vaccinated (with heat-killed yeast cells), and Mycobacterium bovis BCG-treated mice and the mycelial and yeast phases of Histoplasma capsulatum were observed. Phagocytosis of microconidia, small hyphal fragments, and yeast cells occurred 4 to 6 h after the infection of macrophage cultures. Conversion to the yeast phase began at 6 to 7 h and was complete after a 72-h incubation at 370C.

Thtep-nitro-a-acetylamino-pi-hydroxypropiophenone (NAP) differential test for the identification ofMycobacterium tuberculosis recovered from clinical specimens was evaluated by two laboratories and found to be a rapid and accurate procedure with a specificity exceeding 99%.

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A simple method for positive identification of Histoplasma capsulatum, BlastomYces dermatitidis, and Sporothrix schenckii is given. Primary tissue