Acanthamoeba

It is a free living amoeba that causes infections of the eye, skin and CNS which can be rapidly fatal. Trophozoites are the infective form. Acanthamoeba keratitis can follow contact lens use and can cause blindness. Organisms enter the body through minor cuts or are inhaled into the lungs. They have been isolated from soil, air, sewage, seawater, chlorinated swimming pools, domestic tap water, bottled water, dental treatment units, hospitals, air-conditioning units and contact lens cases. Granulomatous amoebic encephalitis is a severe form presenting acutely with fever, headache, seizures, delirium, cranial nerve palsies rapidly progressing to death. Keratitis presents with eye pain, redness, photosensitivity, foreign body sensation and eye watering. Skin lesions present as granulomas. Diagnosis is done by demonstration of trophozoites in csf and brain biopsy. Culture is difficult and is done as a co-culture with E.coli. Corneal scrapings and confocal microscopy can be used for diagnosis of keratitis.

Cyst of Acanthamoeba sp. from brain tissue, stained with hematoxylin and eosin (H&E).