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Chronic Granulomatous Encephalitis

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Chronic Granulomatous Encephalitis, Granulomatous Amoebic Encephalitis, Granulomatous Amebic Encephalitis, Acanthamoeba, Balamuthia mandrillaris

  • See Also
  1. Primary Amebic Meningoencephalitis
  • Pathophysiology
  1. Exposure via fresh water and moist soil
  2. Transmission via respiratory route or via broken skin
  • Causes
  1. Acanthamoeba
    1. Genus of motile, unicellular eukaryotic amoebae with spiny surface projections (acanthopodia)
    2. Free-living amoeba found in fresh water and moist soil
    3. Cause infections in Immunocompromised patients (e.g. AIDS)
    4. Other infections due to Acanthamoeba
      1. Cutaneous acanthamebiasis
      2. Amoebic Keratitis (including Contact LensKeratitis)
  2. Balamuthia mandrillaris
    1. Free-living soil amoeba causing Encephalitis in both immunocompetent and Immunocompromised patients
    2. Also causes Granulomatous skin lesions (which may precede Encephalitis)
    3. Infections are not uncommon, but typically asymptomatic
      1. However amoebic Encephalitis is fatal in most cases
  • Findings
  1. Gradual onset of Granulomatous Encephalitis
  • Labs
  1. Acanthamoeba
    1. Trophozoites and cysts may be seen on microscopy of stained tissue samples
    2. Organisms are elusive on CSF samples
  2. Balamuthia mandrillaris
    1. Immunofluorescence or Immunoperoxidase staining of tissue sample
    2. PCR may be available
  • Differential Diagnosis
  1. See Meningitis
  2. See Encephalitis
  3. Primary Amebic Meningoencephalitis (Naegleria Fowleri)
    1. Acute, rapidly progressive and rapidly fatal
  • Management
  • Adults
  1. Acanthamoeba
    1. Start
      1. Pentamidine IV AND
      2. Fluconazole IV AND
      3. Miltefosine 50 mg orally three times daily
    2. Additional agents may be added
      1. Trimethoprim Sulfamethoxazole
      2. Metronidazole
      3. Azithromycin
  2. Balamuthia mandrillaris
    1. Start
      1. Albendazole AND
      2. Fluconazole or Itraconazole AND
      3. Miltefosine 50 mg orally three times daily
    2. Additional agents may be added
      1. Pentamidine
  • References
  1. Gladwin, Trattler and Mahan (2014) Clinical Microbiology, Medmaster, Fl, p. 339-40
  2. Freedman (2024) Amebic Meningoencephalitis, Sanford Guide, accessed 6/25/25