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[Microbiology](https://durgical.com/en/microbiology/) · [Fungi](https://durgical.com/en/microbiology/#d-fungus)

# 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

## Key points

- Candida forms pseudohyphae and is the yeast most often grown from blood cultures
- Cryptococcus is the encapsulated yeast: India ink and capsular antigen in CSF
- Pneumocystis lacks ergosterol: azoles and amphotericin do not work; it is treated with trimethoprim-sulfamethoxazole
- WHO placed C. albicans, C. auris and C. neoformans in the critical group of its fungal priority pathogens list (2022)

## Microorganisms in this group

- [**Candida albicans** A 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](https://durgical.com/en/microbiology/candida-albicans/)
- [**Cryptococcus neoformans** A 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](https://durgical.com/en/microbiology/cryptococcus-neoformans/)
- [**Pneumocystis jirovecii** An atypical fungus that cannot be cultured; it causes severe pneumonia in advanced HIV or other immunosuppression. Prevented with trimethoprim-sulfamethoxazole. Exam priority: medium](https://durgical.com/en/microbiology/pneumocystis-jirovecii/)
- [**Malassezia** A 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](https://durgical.com/en/microbiology/malassezia/)

## 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.

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Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Candidiasis Basics](https://www.cdc.gov/candidiasis/about/index.html) (CDC, 2024); [About Cryptococcosis](https://www.cdc.gov/cryptococcosis/about/index.html) (CDC, 2024); [WHO releases first-ever list of health-threatening fungi](https://www.who.int/news/item/25-10-2022-who-releases-first-ever-list-of-health-threatening-fungi) (WHO, 2022); [WHO fungal priority pathogens list to guide research, development and public health action](https://www.who.int/publications/i/item/9789240060241) (WHO, 2022).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/microbiology/groups/yeasts-and-yeast-like-fungi/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/microbiology/groups/yeasts-and-yeast-like-fungi/