Which organism is commonly identified by capsule staining with mucicarmine?

• A. Candida albicans
• B. Cryptococcus neoformans
• C. Aspergillus fumigatus
• D. Histoplasma capsulatum

Answer: (B)

Staining the capsule with mucicarmine highlights a distinctive feature of Cryptococcus neoformans. This yeast carries a large polysaccharide capsule that binds mucicarmine, causing the capsule to appear pink to red around the yeast cell. That capsule halo is visible in tissue sections and is a key diagnostic clue for cryptococcosis.

Other fungi listed do not have a capsule that mucicarmine highlights in the same way. Candida albicans lacks a true capsule, so there isn’t a mucicarmine-positive halo to reveal. Aspergillus fumigatus is a mold with hyphae and conidia and does not show a mucicarmine-stained capsule. Histoplasma capsulatum is a small intracellular yeast that also lacks a capsule detectable by this stain.

So, the characteristic capsule staining with mucicarmine most reliably identifies Cryptococcus neoformans.