Resistance of a Pyrimethamine-Resistant Strain of Plasmodium gallinaceum to Certain 2,4-Diaminopyrimidines and Relatad Compounds

Abstract
Seven diaminopyrimidines (including pyrimethamine), chlorguanide, and a diaminotriazine were tested against a pyrimethamine-resistant strain of P. gallinaceum. The strain was 64-fold resistant to pyrimethamine. It showed relatively little resistance (2-fold) to some chemically related compounds and marked cross-resistance (64- to 512-fold) to others. It was about 16-fold resistant to chlorguanide and 8-fold resistant to a diaminotriazine related to chlorguanide.