In vitro effects of antiprotozoan drugs and immune serum on Pneumocystis carinii.

The in vitro survival of Pneumocystis carinii isolated from the lungs of rats with glucocorticoid-induced pneumocystosis has been evaluated by quantitation of uptake of vital dyes by the organisms after exposure to a variety of drugs, immune serum, and medium enriched with macrophage lysosomal enzyme. On the basis of these tests, it appears that pentamidine and chloroquine are directly lethal to the organisms, but that suramin, trimethoprim, and sulfamethoxazole are not. Neither immune serum supplemented with complement and lysozyme nor the supernatant of phagocytosing macrophages appeared to affect the viability of the organisms. Inhibitors of glucose uptake and metabolism appeared to kill Pneumocystis, but neither cycloheximide nor iododeoxyuridine was effective.