Acanthamoeba

A microscopic organism, an amoeba, found in soil, dust and fresh water (lakes, rivers, hot springs and hot tubs). Acanthamoeba also occur in brackish water and sea water as well as in heating, venting, and air conditioner units, humidifiers, and dialysis units. Acanthamoeba can enter the skin through a cut, wound, or through the nostrils and, once inside the body, can travel to the lungs and through the bloodstream to other parts of the body, especially to the central nervous system (the brain and spinal cord). Through improper storage, handling, and disinfection of contact lenses, Acanthamoeba can enter the eye and there cause infection. A particularly dire infection caused by Acanthamoeba called granulomatous amebic encephalitis is characterized by headache, stiff neck, nausea, vomiting, confusion, loss of balance, seizures, and coma that can progress over several weeks and end in death. Acanthamoeba infections occur more frequently in people with compromised immune systems and the chronically ill. Eye and skin infections are generally treatable while infections of the brain are almost always fatal.

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A genus of free-living ameba (family Acanthamoebidae, order Amoebida) found in and characterized by the presence of acanthopodia. Human infection includes invasion of skin or colonization following injury, corneal invasion and colonization, and possibly lung or genitourinary tract colonization; a few cases of brain or CNS invasion have occurred, but not solely by the olfactory epithelium route of entry as with the more virulent infections caused by Naegleria fowleri. Species responsible are chiefly A. culbertsoni, but cases have been reported involving A. castellanii, A. polyphaga, and A. astronyxis, though most cases have been chronic rather than fulminating and rapidly fatal as with Naegleria fowleri infection. [G. akantha, thorn, spine, + Mod. L. amoeba, fr. G. amoibe, change]

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acanth·amoe·ba ə-.kanth-ə-'mē-bə n

1) cap a genus of free-living amebas (family Acanthamoebidae of the order Amoebida) found esp. in soil and freshwater either in the form of feeding and asexually replicating trophozoites or dormant double-walled cysts and including several (as A. culbertsoni and A. castellanii) which are pathogenic in humans causing infections of the skin, respiratory tract, eye (as keratitis esp. in contact lens wearers), and brain (as meningoencephalitis esp. in immunocompromised individuals)

2) any of the genus Acanthamoeba of amebas

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n.

a genus of amoebae that are commonly found in soil and contaminated water and cause painful corneal infection and ulcers in humans, usually resulting from improper sterilization of contact lenses.

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Acan·tha·moe·ba (ə-kan″thə-meґbə) [acanth- + amoeba] a genus of free-living ameboid protozoa of the order Centramoebida found usually in fresh water or moist soil. Certain species, such as A. astronyxis, A. castellanii, A. culbertsoni, A. hatchetti, A. polyphaga, and A. rhysodes, may occur as human pathogens. See also acanthamebiasis.