Molecular epidemiology of malaria in Cameroon. XXVI. Twelve-year in vitro and molecular surveillance of pyrimethamine resistance and experimental studies to modulate pyrimethamine resistance /Tahar, Rachida /Basco, Leonardo In vitro pyrimethamine response of Plastnodium fulciparum isolates and dihydrofolate reductase (dhfr) gene sequences were analyzed in 2004-2005 and compared with our previous data. Most isolates (n = 103, all dhfr mutants) had 50% inhibitory concentrations (IC(50)s) >= 119 nM, and six isolates had low IC(50)s (five wild-type or mixed dhfr, 0.04-1.37 nM; one triple mutant, 6.4 nM). Of 194 isolates, only 7 had the wild-type dhfr and 187 were mutants. The results of the two methods were highly concordant and indicated a significant increase (P < 0.05) in the prevalence of mutant, pyrimethamine-resistant P. falciparum between 1994 and 2005. The addition of probenecid or sulfinpyrazone to pyrimethamine resulted in a slight-to-moderate decrease in the level of in vitro pyrimethamine resistance without rendering the parasites susceptible to pyrimethamine. Analysis of molecular markers may be useful for the long-term surveillance of antifolate-resistant malaria. 2007 text https://www.documentation.ird.fr/hor/fdi:010040786 fdi:010040786 Tahar Rachida, Basco Leonardo. Molecular epidemiology of malaria in Cameroon. XXVI. Twelve-year in vitro and molecular surveillance of pyrimethamine resistance and experimental studies to modulate pyrimethamine resistance. 2007, 77 (2), 221-227 EN CAMEROUN