Acanthamoeba spp.

Lisa A. Spacek, M.D., Ph.D.
Acanthamoeba spp. is a topic covered in the Johns Hopkins HIV Guide.

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MICROBIOLOGY

  • Eight species described: A. castellanii, A. polyphaga, A. culbertsoni, A. hatchetti, A. rhysodes, A. lugdunensis, A. quina, A griffini.[12]
  • Ubiquitous in nature: isolated from air, soil, fresh water, salt water, chlorinated swimming pools, sewage, heating and ventilation systems.
  • Two-stage life cycle
    • Actively feeding and dividing trophozoites that are pleomorphic, without flagella, and 14-40 μm in diameter.
    • Dormant cysts are double-walled, 10-25 μm in diameter, and resistant to chlorine, low temperature, antibiotics, pH extremes.
      • Three groups (I, II, III) of Acanthamoeba spp. based on cyst morphology.[13]
      • Encystation occurs under environmental stress: food deprivation, desiccation, change in temperature.
  • Transmission: inhalation most common route with hematogenous spread; direct inoculation of skin.
  • Described as “Trojan horses” as they can harbor intracellular bacteria, referred to as endosymbionts, which benefit by increased survival or enhanced pathogenicity from interacting with Acanthamoeba.[7][3]

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MICROBIOLOGY

  • Eight species described: A. castellanii, A. polyphaga, A. culbertsoni, A. hatchetti, A. rhysodes, A. lugdunensis, A. quina, A griffini.[12]
  • Ubiquitous in nature: isolated from air, soil, fresh water, salt water, chlorinated swimming pools, sewage, heating and ventilation systems.
  • Two-stage life cycle
    • Actively feeding and dividing trophozoites that are pleomorphic, without flagella, and 14-40 μm in diameter.
    • Dormant cysts are double-walled, 10-25 μm in diameter, and resistant to chlorine, low temperature, antibiotics, pH extremes.
      • Three groups (I, II, III) of Acanthamoeba spp. based on cyst morphology.[13]
      • Encystation occurs under environmental stress: food deprivation, desiccation, change in temperature.
  • Transmission: inhalation most common route with hematogenous spread; direct inoculation of skin.
  • Described as “Trojan horses” as they can harbor intracellular bacteria, referred to as endosymbionts, which benefit by increased survival or enhanced pathogenicity from interacting with Acanthamoeba.[7][3]

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Last updated: December 8, 2019