Successful Chemoprophylaxis for Pneumocystis carinii Pneumonitis

In a randomized, double-blind, placebo-controlled study to evaluate the efficacy of trimethoprim–sulfamethoxazole for the prevention of Pneumocystis carinii pneumonia, we studied 160 patients with cancer who were at high risk for this pneumonia over a two-year period. Seventeen of the 80 patients receiving a placebo acquired P. carinii pneumonitis, whereas none of the 80 given 150 mg of trimethoprim and 750 mg of sulfamethoxazole per square meter per day had the infection (P<0.01). Bacterial sepsis, pneumonia other than that caused by P. carinii, acute otitis media, upper-respiratory-tract infections, sinusitis and cellulitis occurred less frequently in recipients of the drug than in the placebo group (P<0.01 in each case). Oral candidiasis was the only adverse effect encountered from trimethoprim–sulfamethoxazole administration. The study shows the combination to be highly effective in the prevention of P. carinii pneumonitis. (N Engl J Med 297:1419–1426, 1977) Pneumocystis carinii pneumonitis is a major cause of morbidity and mortality in patients undergoing immunosuppressive therapy. Even when treated with pentamidine isethionate, 32 per cent of the cases are fatal.¹ This infection is the most frequent cause of death in patients with acute lymphoblastic leukemia who are in continuous remission.² Recent studies have demonstrated that the attack rate for this infection increases with the extent and intensity of immunosuppressive chemotherapy and irradiation.³ This relation poses a major obstacle to the control of neoplasms that respond best to multiple-drug combinations and intensive radiotherapy. Thus, a more successful outcome of some neoplasms,.