PetriKey

Fungus

Cryptococcus gattii

Encapsulated yeast affecting immunocompetent hosts

krip-toh-KOK-us GAT-ee-eye

yeastcapsulecnsimmunocompetentenvironmentalcryptococcus

High-yield clue

Encapsulated yeast causing meningitis or a mass-like lesion (cryptococcoma) in an immunocompetent host is the core study clue.

Overview

An encapsulated environmental yeast related to Cryptococcus neoformans that classically causes lung and CNS disease in apparently immunocompetent people. Key teaching contrast to C. neoformans on host status and geography.

Classification

  • Encapsulated yeast
  • Basidiomycota
  • Narrow-based budding
  • Polysaccharide capsule
  • Environmental (tree-associated)

Lab & identification clues

  • Encapsulated narrow-based budding yeast microscopy vocabulary
  • Capsule highlighted by negative-stain preparation vocabulary
  • Cryptococcal antigen shared with C. neoformans vocabulary
  • Melanin/urease positivity as genus vocabulary

Associations

  • Disease in immunocompetent hosts more often than C. neoformans
  • Emerged in the Pacific Northwest/Vancouver Island vocabulary
  • Classic association with eucalyptus and other trees
  • Cryptococcoma mass lesions and meningoencephalitis vocabulary

Commonly confused with

  • Cryptococcus neoformans (pigeon-associated, mostly immunosuppressed hosts)
  • Candida species (yeast, no large capsule)

Your notes

Original student-study summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment, dosing, or specimen-handling guidance.

OpenStax: Microbiology 2e organism classification foundationssourceNCBI Bookshelf: Medical Microbiology organism chapterssourceCDC: CDC disease and public-health topic pagessource