Objectives: To determine the in vitro activity of antimalarial drugs against isolates of Plasmodium falciparum in Gabon.
Methods: Plasmodium falciparum isolates were collected from symptomatic infections in the hospitals of Bakoumba and Franceville, south-east Gabon and in 2000. In vitro activity of chloroquine, quinine, mefloquine, halofantrine was measured by the isotopic microtest.
Results: A total of 60 and 62 isolates gave interpretable data in Franceville and Bakoumba, respectively. In Franceville, 50.0% (mean IC50 = 111.7 nm), 0% (mean IC50 = 156.7 nm), and 21.2% (mean IC50 = 12.4 nm) of isolates, respectively, showed in vitro resistance to chloroquine, quinine and mefloquine. In Bakoumba, we saw resistance to chloroquine, quinine, mefloquine and halofantrine in 95.0% (mean IC50 = 325.8 nm), 10.2% (mean IC50 = 385.5 nm), 47.5% (mean IC50 = 24.5 nm) and 18.2% (mean IC50 = 1.9 nm) of isolates, respectively. Activities of chloroquine and mefloquine, chloroquine and quinine, and mefloquine and quinine were positively correlated.
Conclusions: Antimalarial drug resistance is high in this area of Gabon. The extent of resistance is disparate, as all tested drugs were less efficacious in Bakoumba than in Franceville.