Assessment of Plasmodium falciparum Resistance to Piperaquine in Western Kenya using Piperaquine Survival Assay and Molecular Marker Analyses
Malaria is a significant public health burden especially in sub-Saharan AfricarnsSA. Chemotherapy is central in the control of malaria. Piperaquine PPQ in combination withrndihydroartemisinin DHA is the recommended second-line antimalarial for prolonged prophylaxis inrnKenya. The shift to this regimen was driven by increased reports of quinine resistance and decliningrnartemether-lumefantrine Coartem efficacy a first line drug. However the widespread use of DHAPPQ in Kenya may be a short lived solution if PPQ resistance such as that observed in South EasternrnAsia SEA spread to Kenya. It is therefore important to establish PPQ susceptibility in Kenya usingrnpiperaquine survival assay PSA and molecular marker analyses.
establish PPQ susceptibility in Kenya usingrnpiperaquine survival assay PSA and molecular marker analyses.
2-3 ml of clinical isolates collected from P. falciparum naturally infected individualsrnpresenting with uncomplicated malaria at Kombewa sub county hospital and Kisumu county hospitalrnwere tested for piperaquine susceptibility using immediate ex-vivo and in-vitro PSA. A subset of thernisolates was analyzed for in vitro susceptibility using SYBR Green 1-based method. Further eachrnisolate was genotyped for piperaquine resistance markers in targeted codons of Pfcrt Pfmdr1 Pfpm2rnPfpm3 Pfexo and Pfk13 genes using qPCR and the MassARRAY platform.
A total of 40 clinical isolates showed PSA median interquartile range of 0 0-11.02rnn40 at 95 CI. of these 34/40 85 clinical isolates had PSA 10 depicting sensitivity to PPQ.rnSix isolates 15 had PSA of 10 consistent with PPQ resistance Data on treatment and clinicalrnoutcome for these subjects were not available. PPQ median IC50 interquartile range for the subsetrnof clinical isolates in vitro was 20.81 nM 17.33-42.26 n20. A statistically significant positivernassociation was observed between PPQ IC50 and Pfcrt K76T p0.0007 Pfdhps A437G p0.0167rnand A613S p0.0043 respectively. Re-culture for in vitro testing and analyses of polymorphisms inrnPfcrt Pfmdr1 Pfpm2 Pfpm3 Pfexo and Pfk13 genes for these samples are underway.
These finding show that circulating malarial parasites isolated from Kenyan subjectsrnare sensitive to PPQ. The findings on the putative markers of PPQ resistance provide baseline statusrnfor continued monitoring of PPQ susceptibility as DHA-PPQ continues to be widely embraced as arnsecond-line treatment in the country. Our previous studies showing extensive genotype changes in thisrnregion herald the need for genetic studies focusing on samples with PSA survival rate 10 for timelyrndetection of changes.
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Publication Date: 01.Jan.1970
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