PetriKey

Disease

Cryptococcal meningitis

Subacute AIDS meningitis, India ink positive

krip-toh-KOK-ul

fungusyeastmeningitishivopportunistic

High-yield clue

Subacute headache and fever with high CSF pressure in a patient with CD4 below 100, plus a positive India ink or CSF cryptococcal antigen (CrAg), is the classic clue.

Overview

A fungal meningoencephalitis from Cryptococcus, chiefly in advanced HIV, studied for its indolent onset, raised intracranial pressure, and encapsulated-yeast CSF clues.

Classification

  • Fungal meningoencephalitis syndrome
  • Cryptococcus neoformans (encapsulated yeast)
  • AIDS opportunistic infection
  • Inhalation followed by CNS spread

Lab & identification clues

  • India ink encapsulated budding yeast vocabulary
  • CSF cryptococcal antigen (CrAg) latex agglutination
  • Elevated CSF opening pressure vocabulary

Associations

  • At-risk: AIDS with CD4 below 100 cells/uL
  • Environmental exposure to pigeon droppings and soil
  • Subacute headache, fever, and altered mentation vocabulary
  • Raised intracranial pressure complication

Commonly confused with

  • Tuberculous meningitis
  • Bacterial meningitis
  • Toxoplasma encephalitis

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