Mechanism of amphotericin B resistance in clinical isolates of Leishmania donovani

Bidyut Purkait, Ashish Kumar, Nilay Nandi, Abul Hasan Sardar, Sushmita Das, Sudeep Kumar, Krishna Pandey, Vidyananda Ravidas, Manish Kumar, Tripti De, Dharmendra Singh, Pradeep Das

Research output: Contribution to journalArticlepeer-review

220 Scopus citations


The clinical value of amphotericin B, the mainstay therapy for visceral leishmaniasis in sodium antimony gluconatenonresponsive zones of Bihar, India, is now threatened by the emergence of acquired drug resistance, and a comprehensive understanding of the underlying mechanisms is the need of the hour. We have selected an amphotericin B-resistant clinical isolate which demonstrated 8-fold-higher 50% lethal doses (LD50) than an amphotericin B-sensitive strain to explore the mechanism of amphotericin B resistance. Fluorimetric analysis demonstrated lower anisotropy in the motion of the diphenylhexatriene fluorescent probe in the resistant strain, which indicated a higher fluidity of the membrane for the resistant strain than for the sensitive strain. The expression patterns of the two transcripts of S-adenosyl-L-methionine:C-24-Δ-sterol methyltransferase and the absence of ergosterol, replaced by cholesta-5,7,24-trien-3β-ol in the membrane of the resistant parasite, indicate a decreased amphotericin B affinity, which is evidenced by decreased amphotericin B uptake. The expression level of MDR1 is found to be higher in the resistant strain, suggesting a higher rate of efflux of amphotericin B. The resistant parasite also possesses an up-regulated tryparedoxin cascade and a more-reduced intracellular thiol level, which helps in better scavenging of reactive oxygen species produced by amphotericin B. The resistance to amphotericin B was partially reverted by the thiol metabolic pathway and ABC transporter inhibitors. Thus, it can be concluded that altered membrane composition, ATP-binding cassette transporters, and an upregulated thiol metabolic pathway have a role in conferring amphotericin B resistance in clinical isolates of Leishmania donovani.

Original languageEnglish (US)
Pages (from-to)1031-1041
Number of pages11
JournalAntimicrobial agents and chemotherapy
Issue number2
StatePublished - Feb 2012

ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)
  • Infectious Diseases


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