Fungal Meningitis

There are various fungi that may cause meningitis. The manifestations vary by causative organism and host immune status. Some organisms are more common in certain geographical locations. Patients may present acutely with headache and encephalopathy or may have a much more indolent course.


Cryptococcal meningitis:


Cryptococcosis (Cryptococcus neoformans)


Clinical findings plus isolation of the cryptococcus neoformans organism or identification of cryptococcal antigen

Findings on investigation:

CSF analysis:

  • Cryptococcus antigen: positive. 95% sensitive
  • India Ink stain: positive, 50% sensitive, white capsule, pale nucleus
  • WCC: high opening pressure, lymphocytosis in low counts, reduced glucose but may be normal, elevated protein,

Blood, in disseminated infection:

  • Blood cryptococcal antigen: positive, false positive in patients with positive rheumatoid factor RF
  • Isolator cultures: positive
  • Fungal culture:
    • For 6 weeks at 37 degrees


  • Hypodensity suggest infarcts
  • Hydrocephalus


  • Findings of infarcts may occur
  • Hydrocephalus
  • T2: Basal ganglia hyperintense cysts (gelatinous pseudocysts), T1 +GAD: mildly enhancing
  • Gyral enhancement


  • Findings of vasculitis may occur


  • Findings of vasculitis may occur

Other tests:

  • CXR: pulmonary infiltrates +/- lymphadenopathy may occur. May be negative in pulmonary disease. Bronchoalveolar lavage (BAL) culture or cryptococcal antigen positive

Pathology, Biopsy:

  • Immunocompetent patients: Focal granuloma, macrophages, microglia
  • Immunodeficient patient: no or minimal inflammation
  • H&E: clear capsule, blue nucleus, involves Virchow-Robin spaces. More organisms in immunodeficient patients.
  • Meninges: GMS stain, Cryptococcus organisms
  • India ink CSF: white capsule, pale nucleus

Cryptococal meningitis treatment:

  • Amphotericin B
  • Fluconazole

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