In vitro antileishmanial drug susceptibility of clinical isolates from patients with Indian visceral leishmaniasis--status of newly introduced drugs.

Regional variations in susceptibility of Leishmania donovani clinical isolates have been reported to antimonials but not other antileishmanial drugs. Therefore, we evaluated the susceptibility of four antileishmanial drugs in clinical use in 28 clinical isolates from endemic and non-endemic regions in the J774A.1 macrophage cell line, and we found increased tolerance of miltefosine and paromomycin in isolates from a patient from a high endemic region. Effective dose for 90% killing (ED(90)) values were significantly higher for miltefosine (P = 0.005) and paromomycin (P = 0.02) in isolates from the high endemic region, although there were no significant differences between ED(50) values for paromomycin, miltefosine, and amphotericin B in the non- versus endemic region isolates. This report is the first of higher ED(90) values for miltefosine and paromomycin indicating susceptibility difference between regions for these newly introduced drugs by the parasite, and their use should be carefully monitored through directly observed therapy or multidrug treatment to preserve their efficacy for longer periods.