Investigation of the in vitro cysticidal activity of miltefosine against Acanthamoeba spp.

The present study evaluated the in vitro efficacy of miltefosine against cysts of Acanthamoeba spp. belonging to genotypes T3, T4 and T5. Each genotype was incubated with miltefosine at the concentration of 2.42, 4.84, 9.68, 19.36, 38.72 and 77.44 mM for different periods; 1, 3, 5, 7 d at 37 °C. The viability was assessed by staining with 0.4% trypan blue and culturing on NNA medium at 30 °C for 1 month. The results showed 100% eradication of cyst stage of all concentrations, but exhibited a different degree of activity against different genotypes. The MCC of 38.72 mM could kill genotype T4 and T5 after 1 d of incubation, whereas the killing of T3 needed MCC of 77.44 mM at the same incubation time. Miltefosine showed statistically highly significant difference (P < 0.001) in comparison to non-treated control. Although our finding needs to confirm in animal models, this information may be the guideline for optimizing therapy or considered to combine with the other drugs for effective treatment.