Candida albicans yeast produces pseudohyphae, regular clusters of blastoconidia along the points of septation, and large, spherical chlamydospores (Image H). Observing these features in a cornmeal agar preparation helps identify germ tube-negative strains of C. albicans.
C. dubliniensis is similar in appearance to C. albicans on cornmeal agar. It has terminal chlamydospores that occur in pairs or clusters.
When grown on cornmeal agar, Geotrichum species are characterized by true hyphae that segment into rectangular arthroconidia. Arthrospores germinate from one corner, giving them a "hockey stick" appearance (see Image I).
Candida parapsilosis produces a crop of separated foci of growth that show radiating pseudohyphae and scattered blastoconidia, producing what are known as "spider" or "crossed matchstick" colonies (
Image J).
Candida kefyr (previously known as pseudotropicalis) produces elongated blastoconidia that tend to line up along the pseudohyphae in a "logs in stream" arrangement (Image K).
Neither Cryptococcus neoformans nor Candida (previously known as Torulopsis) glabrata produce pseudohyphae. C neoformans are large, spherical, irregular in size, and thick-walled, with spaces between cells, indicative of capsules (Image L). Candida (Torulopsis) glabrata are small, uniform in size, and more compactly arranged (Image M).
Rhodotorula also does not produce pseudohyphae. It reproduces by successively budding, producing multilateral, oval yeast cells that may form short chains. It is usually pink to coral in color on cornmeal agar.
Saccharomyces are oval-to-round yeast cells with multilateral budding. Ascospores may be seen when ascospore or Kinyoun stain is used.
Trichosporon produces both hyphae and pseudohyphae. Blastoconidia are present. In older cultures, arthroconidia may also be present.
