- Mar 30, 2007
[FONT="]The free-living amoebae that cause human infections include [FONT="]Acanthamoeba, Naegleria, Balamuthia mandrillaris,[/FONT] and [FONT="]Sappinia diploidea[/FONT]. All 4 genera cause CNS infections that are frequently fatal. These amoebae are distinct from other pathogenic protozoa. They all have a free-living existence, have no human carrier state (which is important in disease transmission), have a limited relationship with the spread of infection and poor sanitation, and have no insect vector.[/FONT]
[FONT="]The pathogenic species of [FONT="]Acanthamoeba[/FONT] include [FONT="]Acanthamoeba castellanii, Acanthamoeba polyphaga, Acanthamoeba culbertsoni, Acanthamoeba palestinensis, Acanthamoeba astronyxis, Acanthamoeba hatchetti, Acanthamoeba rhysodes, Acanthamoeba divionesis, Acanthamoeba quna, Acanthamoeba lugdunensis,[/FONT] and [FONT="]Acanthamoeba griffini.[/FONT] The life cycle consists of 2 stages: a trophozoite (which is 14-40 µm in diameter) and a cyst (which has a double-layered wall with a diameter of 12-16 µm).[/FONT]
[FONT="]Acanthamoeba[/FONT][FONT="] was first established as a cause of human disease in the 1970s. This genus causes 3 clinical syndromes: granulomatous amebic encephalitis (GAE), disseminated granulomatous amebic disease (eg, skin, sinus, and pulmonary infections), and amebic keratitis. Patients who develop GAE or disseminated disease are usually immunocompromised, whereas those with amebic keratitis are usually immunocompetent. The outcomes of disseminated disease and GAE are poor, and treatment strategies are not well defined; [/FONT]
[FONT="]Acanthamoeba[/FONT][FONT="] keratitis[/FONT][FONT="] is a sight-threatening disease that has favorable prognosis when diagnosed and treated early in the disease course.[/FONT]
[FONT="]The goals of pharmacotherapy are to eradicate the infection, to reduce morbidity, and to prevent complications.[/FONT]
[FONT="]Antifungal Treatment: [/FONT][FONT="]The mechanism of action of these agents may involve an alteration of RNA and DNA metabolism or an intracellular accumulation of peroxide that is toxic to the fungal cell.[/FONT]
Ketoconazole (Nizoral), Itraconazole (Sporanox), Pentamidine (Pentam-300, Pentacarinat, NebuPent), Flucytosine (Ancobon), can be used. Safety of theses drugs during pregnancy has not been established.