In vitro antimalarial drug susceptibility and pfcrt mutation among fresh Plasmodium falciparum isolates from the Lao PDR (Laos)

Mayfong Mayxay, Marion Barends, Alan Brockman, Anchalee Jaidee, Shalini Nair, Dan Sudimack, Tiengkham Pongvongsa, Samlane Phompida, Rattanaxay Phetsouvanh, Tim Anderson, Nicholas J. White, Paul N. Newton

    Research output: Contribution to journalArticlepeer-review

    17 Scopus citations

    Abstract

    Recent drug trials in Laos have shown high levels of Plasmodium falciparum resistance to chloroquine, but there are no published data on in vitro antimalarial drug susceptibility. We used the double-site enzyme-linked pLDH immunodetection (DELI) assay to estimate the in vitro antimalarial drug susceptibility of 108 fresh P. falciparum isolates from southern Laos. The geometric mean (95% confidence interval) 50% inhibitory concentration values (nmol/L) were 152.4 (123.8-187.6) for chloroquine, 679.8 (533.8-863.0) for quinine, 45.9 (37.9-55.7) for mefloquine, 5.0 (4.4-6.4) for artesunate, 6.3 (4.5-8.9) for dihydroartemisinin, and 59.1 (46.4-75.3) for lumefantrine. The proportion of isolates defined as resistant were 65%, 40%, and 8% for chloroquine, quinine, and mefloquine, respectively. Of 53 isolates genotyped for the pfcrt T76K chloroquine-resistance mutation, 48 (91%) were mutants. P. falciparum in Laos is multi-drug resistant; antimalarial immunity resulting from the use of ineffective chloroquine before 2005 probably contributes significantly to the therapeutic responses in clinical trials.

    Original languageEnglish (US)
    Pages (from-to)245-250
    Number of pages6
    JournalAmerican Journal of Tropical Medicine and Hygiene
    Volume76
    Issue number2
    DOIs
    StatePublished - Feb 2007

    ASJC Scopus subject areas

    • Parasitology
    • Virology
    • Infectious Diseases

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