Medications for Acanthamoeba Infections
Acanthamoeba is a genus of ubiquitous, free-living amoebae that inhabit soil, water, and air. Their appearance as corneal pathogens has increased because of several factors, including increased use of contact lenses. The species responsible for corneal infections, which include Acanthamoeba polyphaga, Acanthamoeba castellanii, Acanthamoeba hatchetti, and Acanthamoeba culbertsoni, exist as both trophozoites and double-walled cysts. Because of variations among species of Acanthamoeba, no single drug is effective in treating all cases of Acanthamoeba keratitis. Polyhexamethylene biguanide (0.02% solution) is a non–FDA-approved disinfectant and the first-line agent with the lowest minimal amebicidal concentration. Effective medications include chlorhexidine; neomycin; polymyxin B–neomycin–gramicidin mixtures; natamycin, 5%, topical suspension; imidazoles such as miconazole (powder compounded to 1% topical solution); systemic imidazoles and triazoles; propamidine isethionate, 0.1%, drops (not approved in the United States); and topical dibromopropamidine, 0.15%, ointment (not approved in the United States). Combination therapy is commonly required. See BCSC Section 8, External Disease and Cornea, for further discussion of treatment.
Dart JK, Saw VP, Kilvington S. Acanthamoeba keratitis: diagnosis and treatment update 2009. Am J Ophthalmol. 2009;148(4):487–499.
Seal DV. Acanthamoeba keratitis update: incidence, molecular epidemiology and new drugs for treatment. Eye (London). 2003;17(8):893–905.
Excerpted from BCSC 2020-2021 series: Section 2 - Fundamentals and Principles of Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.