Molecular Evidence for Resistance to Sulfadoxine-Pyrimethamine but Absence of Mutations in Mangaluru, Southwestern India.

In most of India, sulfadoxine-pyrimethamine (SP) artesunate serves as first-line treatment for uncomplicated falciparum malaria. In 112 clinical isolates from Mangaluru, southwestern India, we sequenced molecular markers associated with resistance to SP, lumefantrine, and artemisinin (, , , and ). The double mutation 59R-108N combined with the 437G mutation occurred in 39.3% and the double mutation the double mutation 437G-540E in additional 24.1%. As for , the allele combination N86-184F-D1246 dominated (98.2%). variants were absent. No evidence for artemisinin resistance was seen. However, the antifolate resistance alleles compromise the current first-line antimalarial sulfadoxine-pyrimethamine artesunate, which may facilitate the emergence of artemisinin resistance. Artemether-lumefantrine, introduced in northeastern parts of the country, in the study area faces the predominant NFD genotype, known to impair lumefantrine efficacy. Further monitoring of resistance alleles and treatment trials on alternative artemisinin-based combination therapies are required.