The Effect of Anti-Amoebic Agents and Ce6-PDT on Acanthamoeba castellanii Trophozoites and Cysts, In Vitro

• Published in: Translational vision science & technology 2020-11, Vol.9 (12), p.29-29
• Main Authors: Shi, Lei, Muthukumar, Vithusan, Stachon, Tanja, Latta, Lorenz, Elhawy, Mohamed Ibrahem, Gunaratnam, Gubesh, Orosz, Erika, Seitz, Berthold, Kiderlen, Albrecht F, Bischoff, Markus, Szentmáry, Nóra
• Format: Article
• Language: English
• Subjects: Acanthamoeba castellanii - drug effects; Amebicides - pharmacology; Animals; Escherichia coli; Triazenes; Trophozoites
• ISSN: 2164-2591; 2164-2591
• DOI: 10.1167/tvst.9.12.29

The purpose of this study was to analyze the concentration-dependent effects of biguanides (polyhexamethylene biguanide [PHMB], chlorhexidine [CH]); diamidines (hexamidine-diisethionate [HD], propamidine-isethionate [PD], dibromopropamidine-diisethionate [DD]); natamycin (NM); miltefosine (MF); povidone iodine (PVPI), and chlorin e6 PDT on trophozoites and cysts, in vitro. Strain 1BU was cultured in peptone-yeast extract-glucose medium. Trophozoites or cysts were cultured in PYG medium containing each agent at 100%, 50%, and 25% of maximum concentration for 2 hours. The percentage of dead trophozoites was determined using a non-radioactive cytotoxicity assay and trypan blue staining. Treated cysts were also maintained on non-nutrient agar ( ) plates and observed for 3 weeks. All tested drugs displayed significant cytotoxic effects on 1BU cells based on the biochemical and staining-based viability assays tested. On non-nutrient agar plates, neither trophozoites nor freshly formed cysts were observed after PHMB, PD, NM, and PVPI treatment, respectively, within 3 weeks. However, CH-, HD-, DD-, and MF-treated cysts could excyst, multiply, and encyst again. The off-label drugs PHMB, PD, NM, and PVPI are under in vitro conditions more effective against strain 1BU than CH, HD, DD, and MF. Our findings also suggest that the non-nutrient agar plate assay should be considered as method of choice for the in vitro analysis of the treatment efficacy of anti-amoebic agents. Ophthalmologists may optimize the treatment regime against keratitis by pre-testing the in vitro susceptibilities of the strain against drugs of interest with the non-nutrient agar plate assay.