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|Title:||Laboratory Detection of Artemisinin-Resistant Plasmodium falciparum.|
Day, Nicholas P. J.
Chuor, Char Meng
Dondorp, Arjen M.
White, Nicholas J.
Mahidol University. Faculty of Tropical Medicine. Department of Clinical Tropical Medicine.
Mahidol University. Faculty of Tropical Medicine. Mahidol-Oxford University Tropical Medicine Research Unit.
White, Nicholas J.
|Keywords:||Artemisinin-Resistant;Plasmodium falciparum;Open Access article|
|Citation:||Chotivanich K, Tripura R, Das D, Yi P, Day NP, Pukrittayakamee S. et al. Laboratory Detection of Artemisinin-Resistant Plasmodium falciparum. Antimicrob Agents Chemother. 2014 Jun;58(6):3157-61.|
|Abstract:||Conventional 48-h in vitro susceptibility tests have low sensitivity in identifying artemisinin-resistant Plasmodium falciparum, defined phenotypically by low in vivo parasite clearance rates. We hypothesized originally that this discrepancy was explained by a loss of ring-stage susceptibility and so developed a simple field-adapted 24-h trophozoite maturation inhibition (TMI) assay focusing on the ring stage and compared it to the standard 48-h schizont maturation inhibition (WHO) test. In Pailin, western Cambodia, where artemisinin-resistant P. falciparum is prevalent, the TMI test mean (95% confidence interval) 50% inhibitory concentration (IC50) for artesunate was 6.8 (5.2 to 8.3) ng/ml compared with 1.5 (1.2 to 1.8) ng/ml for the standard 48-h WHO test (P = 0.001). TMI IC50s correlated significantly with the in vivo responses to artesunate (parasite clearance time [r = 0.44, P = 0.001] and parasite clearance half-life [r = 0.46, P = 0.001]), whereas the standard 48-h test values did not. On continuous culture of two resistant isolates, the artemisinin-resistant phenotype was lost after 6 weeks (IC50s fell from 10 and 12 ng/ml to 2.7 and 3 ng/ml, respectively). Slow parasite clearance in falciparum malaria in western Cambodia results from reduced ring-stage susceptibility.|
|Appears in Collections:||TM-Article|
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