[In vitro evaluation of the sensitivity of Plasmodium falciparum to chloroquine using the deli-microtest in region of Dakar, Senegal].
This study was carried out between 2000 and 2001 in the peri-urban Pikine area located 15 km from Dakar, Senegal. The purpose was to evaluate the in vitro sensitivity of Plasmodium falciparum isolates to chloroquine, which was the recommended first-line drug for uncomplicated malaria treatment in Senegal. Testing was carried out using the double-site enzyme-linked lactate dehydrogenase imnunosorbent (DELI) microtest. The DELI-microtest is an ELISA method using 2 monoclonal antibodies against 2 antigenic sites of the specific P. falciparum lactate dehydrogenase (LDH) enzyme. The level of LDH is proportional to the extent of parasite growth. P. falciparum isolates were cultured in 96-well plates in RPMI 1640 medium supplemented with hypoxanthine and albumax, in the presence of chloroquine sulphate concentrations ranging from 5.6 nM/L to 2870.8 nM/L. Plates were incubated in a candle-jar for 48 hours at 37 degrees C and frozen at -20 degrees C. The DELI-microtest was performed using the supernatant of hemolysed cultures. The amount of pLDH released was evaluated based on optical density. The chloroquine sensitivity of the isolate was estimated based on IC50 with a cut-off of <100 nM/L. Geometric mean IC50 values were 41 nM/L (range: 4.8 nM/L to 1435 nM/L) and 135 nM/L (range: 8.63 nM/L to 2153 nM/L) in 2000 and 2001 respectively. This study demonstrated a dramatic increase in the in vitro resistance of P. falciparum to chloroquine from 30% in 2000 to 59.6% in 2001. These findings suggest that regular surveillance of in vitro drug resistance is important to predict in vivo drug resistance and allow timely changes in public health recommendations.
Service de Parasitologie de la Faculte de Médecine, de Pharmacie et d'Odonto-Stomatologie de l'université Cheikh Anta Diop, Dakar, Sénégal. thdieng@refer.sn
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Dieng
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Ndiaye
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Diallo
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Diop
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Brasseur
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Mboup
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Wirth
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Ndir
D000818:Animals; D002738:Chloroquine / Q000494:pharmacology*; D006801:Humans; D021261:Parasitic Sensitivity Tests / Q000379:methods; D010963:Plasmodium falciparum / Q000187:drug effects*; D012675:Senegal
D002738:Chloroquine