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.

In Vitro Amoebicidal Efficacy of Hexamidine, Polyexamethylene Biguanide and Chlorhexidine on Acanthamoeba Ccular Isolates

To evaluate amoebicidal efficacy of various disinfectants, we treated ten ocular isolates of Acanthamoeba with polyhexamethylene biguanide(PHMB), chlorhexidine and hexamidine. Acanthamoeba cysts were collected from axenic nonnutrient agar plates from 4 week culture. Cyst suspension(100microliter) was inoculated on 96-well microplate with concentration of 105 cys/ml. Each well was treated with two-fold diluted hexamidine, PHMB and chlorhexidine(100microliter each, 8 and 48hrs). Each well was examined under the inverted microscope until 7 days after treatment. Minimal cysticidal concentration(MCC) of each disinfectant qas measured after five experiments. MCC of hexamidine, chlorhexidine and PHMB against ten ocular isolates ranged 6.07-500microgram/ml, 3.12-12.50microgram/ml, 1.17-4.68microgram/ml respectively in 48hr treatment. In 8hr treatment, MCC of PHMB and chlorhexidine ranged 4.42-12.50microgram/ml and 4.67-17.71microgram/ml, but hexamidine did not demonstrate cysticidal effect. For proper disinfection of contact lens, disinfectants having cysticidal efficacy should be included in the composition of contact lens solution. Among the currently used topical amoebicidal agents, PHMB showed the greatest cysticidal activity on ten ocular strains of Acanthamoeba in invitro study.