Acanthamoeba castellanii is a free-living amoeba capable of causing keratitis in humans, with most cases related to contact lens wearers and surgical procedures. In addition, A. castellanii may cause pneumonia, granulomatous encephalitis, and skin lesions in immunocompromised individuals. Considering the lack of adequate treatment for acanthamoebiasis, the aim of this review is to assess relevant original articles that covered the current arsenal of drugs and models of organisms used in the field of experimental A. castellanii infection that have been published within the last 5 years (2018–2023) in journals indexed by the following databases: Electronic Library Online (SciELO), PubMed, Medical Literature Analysis and Retrieval System Online (Medline), Latin American and Caribbean Literature in Health Sciences (Lilacs), Google Academic, and Capes Periodical Portal. Thirty articles were selected, and the main findings showed that the available therapeutics for acanthamoebiasis are still limited and nonspecific, and no innovations have occurred in the last few years. In terms of novel chemotherapeutic advances, the last findings have focused on the activity of natural products (plant-based extracts), nanoemulsions, coated particles, and photodynamic association against A. castellanii, without advancing from the bench to bedside perspective. The choice of a non-representative model system for acanthamoebiasis, as well as the limitations of studies in vivo, impairs the advancement of toxicity analyses. Efforts should be made to expand the model systems used, standardize tests for evaluating anti-A. castellanii drug candidates, and increase and support research groups focusing on the biology of A. castellanii and the pharmacology of acanthamoebiasis.

In Brazil, cutaneous leishmaniasis is endemic and may be caused by Leishmania amazonensis. This species is the second most prevalent species in that country, and it is responsible for localized cutaneous and diffuse cutaneous leishmaniasis. Pentavalent antimony is still the first-line drug for cutaneous leishmaniasis treatment in Brazil. In this study, we investigated the in vitro susceptibility to antimony of a panel of L. amazonensis strains and clinical isolates responsible for cutaneous and diffuse cutaneous leishmaniasis. There was a significant variation in susceptibility to antimony not only within these strains and isolates evaluated at either promastigote or intracellular amastigote stages, but also between the two parasite stages for some of these strains and isolates. Additionally, we investigated whether this in vitro susceptibility variation to antimony would affect the in vivo response to treatment, using an experimental BALB/c mouse model of cutaneous leishmaniasis infected with three strains differing in susceptibility. Despite antimony could mildly reduce the lesion size in mice infected with one of these strains, no significant reduction in the parasite burden was found in treated animals, and they were completely refractory to drug treatment. These findings indicate that antimony treatment, even at high dosages via the intraperitoneal route, was not effective against L. amazonensis infection in this animal model. Finally, this study provides a preclinical dataset of the activity of antimony against a panel of strains and isolates of a species responsible for localized cutaneous and diffuse cutaneous leishmaniasis in Brazil.