The therapeutic efficacy of sulfadoxine/pyrimethamine against Plasmodium falciparum in Yemen.
OBJECTIVE
The aim of this study was to determine the sensitivities of Plasmodium falciparum clinical isolates to sulfadoxine/pyrimethamine (SP) using in vivo and in vitro methods.


METHODS
In vivo and Mark III in-vitro test techniques according to World Health Organization protocols of antimalarial drug tests were used to determine the SP susceptibility of the P. falciparum isolates from 100 malaria patients of both sexes between the ages of 3.5 and 45 years and living in Tihamah, Yemen. The study was conducted between 19 March and 12 May 2005.


RESULTS
In vivo: no therapeutic failure occurred; the clinical outcome matched the parasitological response and all patients were parasite free by day 3 and remained so on days 7, 14 and 28. In vitro: all the P. falciparum isolates developed to schizonts in zero-drug-concentration wells, but were inhibited in 40 nmol/l of SP; the mean effective concentration (EC(99)) was 67.17 nmol/l.


CONCLUSIONS
Our findings showed that the SP combination is still effective for the treatment of uncomplicated P. falciparum malaria in Yemen. It is recommended that further studies be carried out to address the importance of dihydropteroate synthetase/dihydrofolate reductase mutations as predictive markers of sulfadoxine/pyrimethamine resistance in Yemen.
Al-Kabsi
Abdulgodos M
AM
Department of Medical Microbiology, Faculty of Medicine and Health Sciences, Sana'a University, and Yemen German Hospital, Sana'a, Yemen.
Al-Shamahy
Hassan A
HA
Al-Harazy
Abdulilah Hussein
AH
Harmal
Nabil S
NS
D000293:Adolescent; D000328:Adult; D000818:Animals; D000962:Antimalarials / Q000494:pharmacology*; D002648:Child; D002675:Child, Preschool; D004351:Drug Resistance; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D016778:Malaria, Falciparum / Q000188:drug therapy* / Q000453:epidemiology; D008297:Male; D008826:Microbial Sensitivity Tests; D010963:Plasmodium falciparum / Q000187:drug effects*; D011739:Pyrimethamine / Q000494:pharmacology*; D052939:Schizonts / Q000187:drug effects; D017678:Sex Distribution; D013413:Sulfadoxine / Q000494:pharmacology*; D015006:Yemen / Q000453:epidemiology; D055815:Young Adult
D000962:Antimalarials; D013413:Sulfadoxine; D011739:Pyrimethamine