Comparison of in vitro chloroquine sensitivity testing with detection of pfmdr1 point mutations in Plasmodium falciparum

There is conflicting evidence about the role in antimalarial drug resistanc e of the putative Plasmodium falciparum multi-drug resistance gene homologu e, pfmdr1. Using a modified version of the World Health Organization's stan dard in vitro microtest, we assessed chloroquine sensitivity of Plasmodium falciparum in Mpumalanga Province, South Africa, and compared the results w ith detection of two specific mutations in pfmdr1 by restriction enzyme dig estion of polymerase chain reaction products (PCR/RD). Successful in vitro chloroquine sensitivity tests indicated a chloroquine resistance rate of 77 .3 % in our sample of 22 specimens. Chloroquine resistance was calculated a t 72.7 % by PCR/RD. There was no significant difference between the results of the two methods (P = 1, McNemar's paired chi(2) test). These results su ggest that it may be worth further investigating the value of PCR/RD analys is for large scale assessment of chloroquine sensitivity in South Africa.