Volume 37, Issue 1
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645



In vitro tests for sensitivity to pyrimethamine, sulfadoxine, and both drugs in combination were performed in four kinds of culture medium, each differing in p-amino benzoic acid (PABA) and folic acid concentrations. Results of the tests using pyrimethamine-sensitive and pyrimethamine-resistant isolates indicated that drug activity was reduced proportionally to the concentrations of these two growth factors in the medium. The optimal concentrations of PABA and folic acid for parasite growth and drug susceptibility, as evaluated by microscopic examination and by the extent of incorporation of radioactive C-pyrimethamine and C-sulfadoxine, were 10 ng/ml and 2 ng/ml, respectively. Depletion of PABA and folic acid from the medium had no effect on drug-resistant parasites but multiplication of drug-sensitive isolates was markedly reduced. Medium containing 0.5 ng/ml PABA and 10 ng/ml folic acid was the best for parasite growth regardless of the degree of drug sensitivity. Results obtained by using this medium agreed most closely with results from in vivo observations.


Article metrics loading...

The graphs shown below represent data from March 2017
Loading full text...

Full text loading...


Most Cited This Month

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error