Yeasts and yeast-like fungi !
- Fungi
Single-celled fungi that reproduce by budding: Candida and Cryptococcus cause the most common opportunistic mycoses in hospitals and in HIV.
Updated 2026-11-01
What they are
Yeasts are single-celled fungi, round or oval, that multiply by budding. Several live on skin or mucosa without harm and cause disease when immunity drops or a barrier breaks. Pneumocystis, an atypical fungus that does not grow in culture, is grouped here too.
What they share
- Single cell that divides by budding
- Creamy colonies on Sabouraud agar, except Pneumocystis, which cannot be cultured
- Many are commensals that cause opportunistic infection
- On a KOH mount they look like round bodies, sometimes with pseudohyphae
Microorganisms in this group
- Candida albicansA yeast living in the mouth, gut and vagina; causes thrush, vaginitis and hospital bloodstream infection. Its relative C. auris is multidrug resistant.Exam priority: high
- Cryptococcus neoformansA yeast with a thick capsule that lives in soil and bird droppings; inhaled, it can cause meningitis, above all in advanced HIV.Exam priority: high
- Pneumocystis jiroveciiAn atypical fungus that cannot be cultured; it causes severe pneumonia in advanced HIV or other immunosuppression. Prevented with trimethoprim-sulfamethoxazole.Exam priority: medium
- MalasseziaA yeast that normally lives on oily skin; with heat and sweat it overgrows and causes pale or dark patches with fine scale on the trunk and arms.For completeness
Test yourself
Think of the answer, then tap the question to see it.
How do yeasts reproduce?
By budding: a bud grows out of the mother cell and separates.
Which yeast in this group is recognised by its thick capsule on India ink?
Cryptococcus neoformans (and C. gattii).
Why does Pneumocystis not respond to azole antifungals?
Its membrane has almost no ergosterol, the target of azoles and amphotericin B.
Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Candidiasis Basics (CDC, 2024); About Cryptococcosis (CDC, 2024); WHO releases first-ever list of health-threatening fungi (WHO, 2022); WHO fungal priority pathogens list to guide research, development and public health action (WHO, 2022).
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Representative model, for educational purposes only.