Depending on cell morphology classified as :
- Yeasts
- Yeast like fungi
- Molds
- Dimorphic fungi
1- Yeasts:
- Unicellular fungi which reproduce by budding On culture – produce smooth, creamy colonies e. g Cryptococcus neoformans (capsulated yeast)
Cryptococcus neoformans yeast cells
2- Yeast like fungi:
- Grow partly as yeasts and partly as elongated cells resembling hyphae which are called pseudo hyphae e.g. Candida albicans.
Candida albicans yeasts and pseudohyphae
3- Molds/ Filamentous fungi:
- Multicellular fungi that form true mycelia & reproduce by formation of different types of spores. Vegetative/ aerial hyphae e.g. Rhizopus, Mucor
Molds – Filamentous fungi
4- Dimorphic fungi:
Occur in 2 forms Molds (Filaments) – 25°C (soil) while Yeasts – 37°C (in host tissue). Most fungi causing systemic infections are dimorphic:
- Histoplasma capsulatum
- Blastomyces dermatidis
- Paracoccidioides brasiliensis
- Coccidioides immitis
- Penicillium marneffei
- Sporothrix schenkii
Illustration of the Life Cycle of the Dimorphic Fungus Histoplasma capsulatum
