Susceptibility of Pneumocystis carinii to artemisinin in vitro.

The susceptibility of Pneumocystis carinii to artemisinin (qinghaosu) was determined in short-term primary culture. In untreated cultures, trophozoites increased an average of fivefold over 4 days. Inhibition of parasite growth in cultures treated with artemisinin at concentrations as low as 0.5 microM was seen. In contrast, artemisinin concentrations up to 100 microM had no effect on feeder layer cells.