In vitro activity of quinolines against Plasmodium falciparum in Gabon

The assessment of drug sensitivity of Plasmodium falciparum to antimalarial drugs is of vital interest for malaria endemic regions. We conducted a follow-up study to monitor the in vitro activity of the most commonly used quinolines against fresh P falciparum isolates in Lambarene, Gabon by measuring schizont maturation inhibition in 2002. Mean 50% effective concentration levels for chloroquine, quinine, and mefloquine were 5.5 mumol/l blood, 286 nmol/l blood medium mixture (BMM), and 1.1 mumol/l blood, respectively. All isolates (n = 40) were found to be highly resistant to chloroquine. One isolate was resistant to mefloquine and five isolates were presenting borderline-resistance. All isolates were inhibited by quinine concentrations below the threshold of resistance (n = 43). Besides the observation of an increasing number of borderline resistant isolates to mefloquine, an extremly high parasite resistance to chloroquine-still officially the first line antimalarial in Gabon-seems to be of particular concern. (C) 2003 Elsevier B.V. All rights reserved.