Drug susceptibility in Leishmania isolates following miltefosine treatment in cases of visceral leishmaniasis and post kala-azar dermal leishmaniasis.
BACKGROUND
With widespread resistance to antimonials in Visceral Leishmaniasis (VL) in the Indian subcontinent, Miltefosine (MIL) has been introduced as the first line therapy. Surveillance of MIL susceptibility in natural populations of Leishmania donovani is vital to preserve it and support the VL elimination program.


RESULTS
We measured in vitro susceptibility towards MIL and paromomycin (PMM) in L. donovani isolated from VL and PKDL, pre- and post-treatment cases, using an amastigote-macrophage model. MIL susceptibility of post-treatment isolates from cured VL cases (n = 13, mean IC(50)±SD = 2.43±1.44 µM), was comparable (p>0.05) whereas that from relapses (n = 3, mean IC(50) = 4.72±1.99 µM) was significantly higher (p = 0.04) to that of the pre-treatment group (n = 6, mean IC(50) = 1.86±0.75 µM). In PKDL, post-treatment isolates (n = 3, mean IC(50) = 16.13±2.64 µM) exhibited significantly lower susceptibility (p = 0.03) than pre-treatment isolates (n = 5, mean IC(50) = 8.63±0.94 µM). Overall, PKDL isolates (n = 8, mean IC(50) = 11.45±4.19 µM) exhibited significantly higher tolerance (p<0.0001) to MIL than VL isolates (n = 22, mean IC(50) = 2.58±1.58 µM). Point mutations in the miltefosine transporter (LdMT) and its beta subunit (LdRos3) genes previously reported in parasites with experimentally induced MIL resistance were not present in the clinical isolates. Further, the mRNA expression profile of these genes was comparable in the pre- and post-treatment isolates. Parasite isolates from VL and PKDL cases were uniformly susceptible to PMM with respective mean IC(50) = 7.05±2.24 µM and 6.18±1.51 µM.


CONCLUSIONS
The in vitro susceptibility of VL isolates remained unchanged at the end of MIL treatment; however, isolates from relapsed VL and PKDL cases had lower susceptibility than the pre-treatment isolates. PKDL isolates were more tolerant towards MIL in comparison with VL isolates. All parasite isolates were uniformly susceptible to PMM. Mutations in the LdMT and LdRos3 genes as well as changes in the expression of these genes previously correlated with experimental resistance to MIL could not be verified for the field isolates.
National Institute of Pathology, Indian Council of Medical Research, Safdarjung Hospital Campus, New Delhi, India.
Vasundhra
V
Bhandari
Arpita
A
Kulshrestha
Deepak Kumar
DK
Deep
Olivia
O
Stark
Vijay Kumar
VK
Prajapati
V
V
Ramesh
Shyam
S
Sundar
Gabriele
G
Schonian
Jean Claude
JC
Dujardin
Poonam
P
Salotra
D000293:Adolescent; D000328:Adult; D000818:Animals; D000981:Antiprotozoal Agents / Q000494:pharmacology* / Q000627:therapeutic use; D002648:Child; D005260:Female; D006801:Humans; D007194:India; D020128:Inhibitory Concentration 50; D007893:Leishmania donovani / Q000187:drug effects* / Q000302:isolation & purification*; D016773:Leishmaniasis, Cutaneous / Q000188:drug therapy* / Q000469:parasitology; D007898:Leishmaniasis, Visceral / Q000188:drug therapy* / Q000469:parasitology; D008264:Macrophages / Q000469:parasitology; D008297:Male; D008875:Middle Aged; D021261:Parasitic Sensitivity Tests / Q000379:methods; D010303:Paromomycin / Q000494:pharmacology / Q000627:therapeutic use; D010767:Phosphorylcholine / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D055815:Young Adult
D000981:Antiprotozoal Agents; D010767:Phosphorylcholine; C039128:miltefosine; D010303:Paromomycin