Acanthamoeba castellanii (A. castellanii)

Acanthamoeba castellanii is a ubiquitous, free-living, opportunistic protozoan pathogen found widely in soil, water, and air environments. It is well-recognized as a primary causative agent of Acanthamoeba keratitis (AK), a sight-threatening corneal infection primarily affecting contact lens wearers, and Granulomatous Amoebic Encephalitis (GAE), a rare but nearly always fatal infection of the central nervous system in immunocompromised patients (Siddiqui & Khan, 2012, Parasites & Vectors). As a therapeutic target, the organism is unique because treatment must address both its active, proliferative trophozoite form and its highly resilient, dormant cyst stage (CDC, 2023). Current clinical strategies utilize multi-drug regimens, including biguanides like chlorhexidine and diamidines like propamidine, which work by disrupting the amoebic cell membrane (Lorenzo-Morales et al., 2015, Trends in Parasitology). Additionally, azole antifungals are often employed to target sterol biosynthesis within the organism. Despite these treatments, the ability of the amoeba to transition into the cyst stage presents a significant therapeutic challenge, often leading to prolonged treatment durations, high rates of recurrence, and significant tissue damage.

Other names

Amoeba castellaniiA. castellanii

Drugs targeting this organism typically act through the disruption of the cytoplasmic membrane (biguanides and diamidines), inhibition of sterol 14-alpha demethylase to prevent ergosterol synthesis (azoles), or interference with phospholipid metabolism and induction of apoptosis-like cell death (miltefosine).