Resistance-mediating polymorphisms of Plasmodium falciparum among isolates from children with severe malaria in Kumasi, Ghana

Abstract

Background: Antimalarial drug resistance has been a major contributor to the failure of the battle against malaria in many developing countries. The P. falciparum genes, pfcrt and pfmdr-1, have been implicated in chloroquine resistance. The objective of this study was to determine the presence of mutant alleles of these chloroquine resistance genes among
isolates of P. falciparum from children presenting with severe malaria in Ghana.
Methods: Venous blood samples were taken from patients, and plasma chloroquine levels measured. P. falciparum chromosomal DNA was isolated from the blood samples, and subjected to PCR, restriction digestion and sequencing. Resulting data were analysed using the STATA statistical software.
Results: Of 140 children recruited into the study, 109 (77.9%) had detectable pre-treatment chloroquine levels. PCR and restriction digestion analysis of the pfcrt gene indicated that 124 (88.6%) had the mutant
T76 gene, and that this correlated with higher chloroquine levels. Sequence analysis of these showed consistent genetic sequences for chloroquine resistant and sensitive parasites with respect to Pfcrt codons 72
through 76.The Pfcrt T76 mutation was found in 88.4% of isolates having the Pfmdr-1Y86 mutation. The Pfmdr-1 Y86 mutation was found in 67.6% of isolates having the Pfcrt T76 mutation.
Conclusion: The study affirms Pfcrt as a better chloroquine resistance marker. Both mutations are independently selected by chloroquine levels and that one mutation (Y86) might modify/increase the effect of
the other (T76). This study also depicts the muchoverlooked antimalarial drug resistance situation in the area and emphasizes the need for a proper treatment strategy.