Susceptibility of clinical isolates of Leishmania aethiopica to miltefosine, paromomycin, amphotericin B and sodium stibogluconate using amastigote-macrophage in vitro model

Cutaneous Leishmaniasis (CL) caused by Leishmania aethiopica is a public health and social problem with a sequel of severe and mutilating skin lesions. It is manifested in three forms: localized CL (LCL), mucosal CL (MCL) and diffuse CL (DCL). Unresponsiveness to sodium stibogluconate (SbV) is common in Ethiopian CL patients. Using the amastigote-macrophage in vitro model the susceptibility of 24 clinical isolates of L. aethiopica derived from untreated patients was investigated. Eight strains of LCL, 9 of MCL, and 7 of DCL patients together with a reference strain (MHOM/ET/82/117/82) were tested against four antileishmanial drugs: amphotericin B, miltefosine, SbV and paromomycin. In the same order of drugs, IC50 (μg/ml ± SD) values for the 24 strains tested were 0.16 ± 0.18, 5.88 ± 4.79, 10.23 ± 8.12, and 13.63 ± 18.74. The susceptibility threshold of isolates originating from the 3 categories of patients to all 4 drugs was not different (p > 0.05). Maximal efficacy was superior for miltefosine across all the strains. Further susceptibility test could validate miltefosine as a potential alternative drug in cases of sodium stibogluconate treatment failure in CL patients.

The photo below shows amastigote suppressive effect of miltefosine at a concentration of 13.3 μg/ml after 5 days incubation at 31 °C, 5% CO2, and 95% relative humidity. The figures on the lower left corner of the photos refer to amastigote density per 25 infected macrophages. Original magnification 1000×.Figure optionsDownload as PowerPoint slideHighlights
► We optimized and sustained infection for five days period of in vitro drug assay.
► We tested drug susceptibility of Leishmania aethiopica from three forms of patients.
► We compared maximal efficacy among four antileishmanial drugs.
► Maximal efficacy attained by miltefosine was superior over the other three drugs.