Slide 1. Cryptococcus neoformans
This cerebrospinal fluid includes large gram-positive yeasts, some with orange halos formed by the polysaccharide capsules. Although cryptococci are sometimes visible with Gram stains, an India-ink preparation is the preferred diagnostic test.

Slide 2. Cryptococcus neoformans
This India-ink preparation demonstrates yeasts with halos, which are the polysaccharide capsules. Inexperienced examiners can confuse lymphocytes with yeasts, but the clear space that surrounds the lymphocytes is usually narrow rather than broad. The presence of budding yeasts is diagnostic. India-ink preparations are positive in about 75% of cryptococcal meningitis patients who also have AIDS. In those who do not have AIDS, the yield is about 50%.

Slide 3. Cryptococcus neoformans (calcofluor white stain)
Many yeast cells are budding and the place where the cells remain attached is narrow (“narrow-based budding”). This characteristic distinguishes it from Blastomyces dermatiditis, whose yeast forms are similar in size but demonstrate broad-based budding.