Assessment of Sensitivity of P. Falciparum to Antifolate Antimalarials In Southern Ghana By Polymerase Chain Reaction (PCR) Assay Systems
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Date
1996-07
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University of Ghana
Abstract
Drug treatment of malaria is being hampered by the emergence of drug resistant strains of malaria parasites. Rapid methods for monitoring patients' response to treatment, applicable to field conditions, would aid management and control of drug resistant P. falciparum infections.
In this study, mutation specific polymerase chain reaction assays using 3'-mismatched oligonucleotide primers which annealed to the wild or mutated parasites gene encoding dihydrofolate reductase-thymidylate synthase (DHFR-TS) were used to survey P.falciparum strains in two Regions of Southern Ghana (Volta and Greater Accra Regions). Mutations were identified directly from blood samples obtained from patients attending Out Patients Departments in Hospitals. Amplified P.falciparum DHFR-TS nucleotide sequences of 337bps were obtained when reaction products were analyzed by electrophoresis. Of 151 smear positive samples analysed, 13 (8.6%) contained the Asn-10S codon AAC that confers pyrimethamine resistance, 133 (88%) samples contained only the wild type Ser-10S codon AGC and none contained the Val-16 codon GTA found in cycloguanil-resistant pyrimethamine sensitive parasites. Out of the 13 pyrimethamine resistant cases, 10 were found in samples obtained from the Volta Region while the rest (3) were from Korle-Bu Teaching Hospital in the Greater Accra Region. No PCR product was found in 5 (3.3%) of the 151 samples. After second (nested) PCR, only one sample showed amplified product: contamination was negligible. PCR amplification of the DHFR-TS presents a rapid alternative to in vitro drug testing for monitoring the resistance of P.falciparum to antifolate antimalarials.
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Keywords
Polymerase Chain Reaction, Antifolate Antimalarials, P. Falciparum