Polymorphisms in cg2 and pfcrt genes and resistance to chloroquine and other antimalarials in vitro in Plasmodium falciparum isolates from Colombia

Abstract Polymorphisms in Plasmodium falciparum cg2 and pfcrt genes and their association with chloroquine resistance in vitro in Colombian parasites were evaluated in this study. Association of chloroquine resistance with resistance to other antimalarial drugs in vitro was also examined. Polymerase chain reactions (PCR) for κ and ω cg2 regions and nested PCR and digestion with Apo I enzyme for K-76T pfcrt point mutation defined corresponding polymorphisms in 83 samples collected between 1995 and 1999. The isotopic microtest was used to evaluate sensitivity in vitro in a subgroup of 18 isolates. The predominant cg2 pattern observed was 13κ/14ω repeats (46/83 [55.4%]) and all samples presented the K-76T mutant allele. Seventy-eight percent of samples were resistant to chloroquine in vitro, 35.3% to amodiaquine, 16.7% to mefloquine, and 5.6% to quinine. Significant correlations ( P 50 s of chloroquine and arteether, and among IC 50 s of arteether, mefloquine, and quinine. These results suggest the development of multiple and cross-resistance of Colombian P. falciparum isolates to second- and third-line antimalarials and new alternative drugs.