Prevalence of polymorphism in Pfdhps & Pfdhfr genes associated sulphadoxine-pyrimethamine resistance among clinical isolates
Dr. Priti Singh
The present study was carried out to evaluate the prevalence of polymorphism of point mutations at position 16, 51,59,108 and 164 of Pfdhfr and at positions 436, 437, 540, 581 and 613 of Pfdhpsgenes in preserved blood samplesof patients with confirmed P. falciparummonoinfection, who were treated with SP only, in 2010, in Kolkata, West Bengal before introduction of ACT in West Bengal, India.This study may be used to assess the usefulness of these molecular marker in determining the future trends of SP resistance. The prevalence of polymorphism of Pfdhfr and Pfdhps gene point mutation in preserved blood samples of patients with confirmed P. falciparum mono infection, who were treated with SP only in 2010, in Kolkata, West Bengal. W.H.O. now recommends use of ACT for the treatment of uncomplicated P. falciparum malaria. As SP monotherapy is no longer in use for falciparum malaria treatment, blood samples of patients with confirmed P. falciparummonoinfection, who attended the malaria clinics, of CSTM during July to December 2010 and who met the W.H.O. inclusion criteria and were treated with SP only, were kept preserved in EDTA vials at -200C in protozoology section of CSTM were used for this study. Through this study, we have tried to characterize the prevalence of mutations in Pfdhfr and Pfdhps genes associated with SP resistance, from isolates collected in 2010 from Kolkata, before the implementation of ACT. We found a high prevalence of mutated allele for both the gene locus (Pfdhfr more than Pfdhps). The absence of quadruple mutation in either gene or absence of sextuple mutation or more in combined haplotypes assures that resistance was not at an alarming level to cause SP treatment failure and so majority of the cases were found to show ACPR. However, this high prevalence also points that if the drug pressure continues to increase ( as SP is being used with ACT), it will lead to further increase in mutations and will finally cause treatment failure as has been seen in North Eastern states of India and many countries of world. Hence an ongoing monitoring is required to know the prevalence of these mutations in different regions, so that timely intervention in drug policy can be done.