Combating Acanthamoeba spp. cysts: what are the options?

Abstract

Acanthamoeba spp. are protist pathogens and causative agents of serious infections including keratitis and granulomatous amoebic encephalitis. Its ability to convert into dormant and highly resistant cysts form limits effectiveness of available therapeutic agents and presents a pivotal challenge for drug development. During the cyst stage, Acanthamoeba is protected by the presence of hardy cyst walls, comprised primarily of carbohydrates and cyst-specific proteins, hence synthesis inhibition and/or degradation of cyst walls is of major interest. This review focuses on targeting of Acanthamoeba cysts by identifying viable therapeutic targets.

Evaluating Potential of Electromagnetic Microwaves on Destruction Acanthamoeba Cysts

“…Cysts of this parasite are resistant to chemical drugs or require overdosage of drugs to eliminate cysts. So finding and using drugs of natural origin or other treatments that destroy the cyst wall or wall synthesis obstacle have been the focus of researchers [17].…”

In Vitro Amoebicidal Activity of Titanium Dioxide/UV-A Combination AgainstAcanthamoeba

“…33 Cyst persistence in tissue is common and a recurrence of infection can follow prolonged topical therapy or surgical therapy. 7 We suspect that lipid peroxidation, 18 release of intracellular components, 19 and nucleic acid 20,21 and protein damage 22,23 are the photocatalytic effects on cysts of the TiO 2 /UV-A combination, as described by bacterial (E. coli) studies. The cytoplasmic membrane damage due to chlorhexidine may facilitate entry into the cysts of oxygenated free radicals and could explain the synergistic effect of chlorhexidine and TiO 2 with UVA observed in vitro on cysts.…”

“…5 The pathogenesis is characterized by two events: (1) trophozoites adhere to the epithelial surface and invade then degrade the stromal extracellular matrix 6 and (2) encystment of the protozoan, which promotes resistance and recurrence of infection. 7 Currently, the treatment involves topical antimicrobials, such as chlorhexidine, polyhexamethylene biguanide, 8 diamidines, 9 and antifungal agents 10 belonging to membraneacting agents. 11 Contrary to bacterial or fungal keratitis, failure of topical therapy is common.…”

Description of Virulent Factors and Horizontal Gene Transfers of Keratitis-Associated Amoeba Acanthamoeba Triangularis by Genome Analysis

“…The A. triangularis trophozoite is an active stage in which the amoeba moves, feeds, and divides. Under harsh unfavorable conditions, such as changes in temperature, pH, lack of nutrients, treatment with disinfectant or therapeutic agents, the amoebas have the ability to adopt a resistant double-walled cyst stage [11]. Free-living amoeba (FLA) food microorganisms, by selective grazing to grow, contribute to the regulation of the environmental microbial population [1,12].…”