The effect of antiamoebic agents and Ce6‐PDT on acanthamoeba castellani trophozoites and cysts, in vitro

Abstract

AbstractPurposeTo analyze the concentration dependent effect of diamidines (hexamidine‐diisethionat (HD), propamidin‐isethionate (PD), dibromopropamidine‐diisethionat (DD)); biguanides (polyhexamethylen biguanid (PHMB), chlorhexidine (CH)); natamycin (NM); miltefosine (MF); povidone iodine (PVPI) and chlorin e6 photodynamic therapy (PDT) on Acanthamoeba castellani trophozoites and cysts, in vitro.MethodsAcanthamoeba castellani strain was cultured in 712 peptone‐yeast extract‐glucose (PYG) medium. Thereafter, trophozoites or cysts were cultured in 0.25–0.1% HD, PD or DD, or 0.005–0.02% PHMB, CH or NM or 0.001625–0.0065 MF or 0.25–1% PVPI containing PYG medium for 2 h or underwent Chlorin e6‐PDT. Then, the percentage of dead trophozoites was determined by CytoTox 96® Non‐Radioactive Cytotoxicity assay and trypan blue staining and those of cysts using trypan blue staining. Treated trophozoites and cysts were also inoculated to non‐nutrient agar Eshericia coli plates and were observed for 5 weeks.ResultsAll concentrations of different antiamoebic agents had a significant cytotoxic effect on AK trophozoites and cysts (p < 0.05), except 0.02% PHMB and CH, using trypan blue assay for trophozoites, and Ce6‐PDT for cysts. Observing the agar plates, HD, PD, PHMB, CH, NM and PVPI led to morphological changes of acanthamoeba trophozoites, which could not form cysts within 5 weeks. DD and MF treated cysts could excyst and later encyst again.ConclusionsConservative treatment using different antiamoebic agents or Ce6‐PDT can not eradicate all Acanthamoeba castellani trophozoites and cysts. In vitro analyzis of treatment efficacy of different antiamoebic agents may alow a more specific treatment in acanthamoeba keratitis.