Plasmodium falciparum: detection of antifolate resistance by mutation-specific restriction enzyme digestion.

We describe here a rapid procedure to predict the resistance of Plasmodium falciparum to pyrimethamine or cycloguanil. The method consists of amplification by PCR of the DHFR gene followed by restriction enzyme digestion of codons 16 and 108. Three different enzymes are used to cut the wild-type, 108-threonine mutant, and 108-asparagine mutant gene. Since every natural antifolate-resistant isolate identified until now carries a mutation in codon 108, determination of the nature of this codon can predict the sensitivity of any P. falciparum isolate.