Clinical and in vitro resistance of Plasmodium falciparum to artesunate-amodiaquine in Cambodia

Melissa Mairet-Khedim, Rithea Leang, Camille Marmai, Nimol Khim, Saorin Kim, Sopheakvatey Ke, Chhayleang Kauy, Nimol Kloeung, Rotha Eam, Sophy Chy, Brigitte Izac, Denis Mey Bouth (+4 others)
2020 Clinical Infectious Diseases  
Background Artesunate-amodiaquine is a potential therapy for uncomplicated malaria in Cambodia. Methods Between September 2016 and January 2017, artesunate-amodiaquine efficacy and safety were evaluated in a prospective, open-label, single-arm observational study at health centers in Mondulkiri, Pursat and Siem Reap Provinces, Cambodia. Adults and children with microscopically-confirmed Plasmodium falciparum malaria received oral artesunate-amodiaquine once daily for three days plus single-dose
more » ... ys plus single-dose primaquine, with follow-up on Days 7, 14, 21 and 28. The primary outcome was Day-28 PCR-adjusted adequate clinical and parasitological response (ACPR). An amodiaquine parasite survival assay (AQSA) was developed and applied to whole genome sequencing results to evaluate potential amodiaquine resistance molecular markers. Results In 63 patients, Day-28 PCR-adjusted ACPR was 81.0% (95% confidence interval [CI], 68.9–88.7). Day 3 parasite positivity rate was 44.4% (28/63; 95%CI, 31.9–57.5). All 63 isolates had the K13(C580Y) marker for artemisinin resistance; 79.4% (50/63) had Pfpm2 amplification. The AQSA resistance phenotype (≥45% parasite survival) was expressed in 36.5% (23/63) of isolates and was significantly associated with treatment failure (P = 0.0020). Pfmdr1 mutant haplotypes were N86/184F/D1246 and Pfcrt was CVIET or CVIDT at positions 72–76. Additional Pfcrt mutations were not associated with amodiaquine resistance, but the G353V mutant allele was associated with ACPR compared to Pfmdr1 haplotypes harboring F1068L or S784L/R945P mutations (P = 0.030 and P = 0.0004, respectively). Conclusions For uncomplicated falciparum malaria in Cambodia, artesunate-amodiaquine had inadequate efficacy owing to amodiaquine-resistant P. falciparum. Amodiaquine resistance was not associated with previously identified molecular markers.
doi:10.1093/cid/ciaa628 pmid:32459308 fatcat:sylv6ornxjdg3cmm4hbb23e5e4