Pneumocystis carinii Pneumonia Treated with Pyrimethamine and Sulfadiazine

Pentamidine isethionate has been considered the only effective agent in the treatment of Pneumocystis carinii pneumonia. Its toxicity makes it less than the ideal drug. Pyrimethamine and sulfadiazine have been as effective as pentamidine in the treatment of P. carinii pneumonia in experimental animals. Results of prior reported treatment in human disease are reviewed. Three consecutive patients with biopsy-proved P. carinii pneumonia who were admitted to the medical service at the University of Texas Medical Branch Hospitals, Galveston, and treated with pyrimethamine and sulfadiazine are reported. Two patients were clinically cured and have had long-term follow-up. One patient showed clinical improvement with therapy but died of unknown causes shortly after completion of treatment; autopsy was not performed. The encouraging results obtained with the use of pyrimethamine and sulfadiazine indicate the need for further clinical trial with these readily available and relatively nontoxic antimicrobial agents.