Sulfamethoxazole-trimethoprim for infections in cancer patients.

A combination of sulfamethoxazole and trimethoprim (Bactrim) was given orally to 35 cancer pattients with infections. Thirty-two patients did not respond to an initial antibiotic regimen that consisted primarily of carbenicillin disodium and an aminoglycoside. There were 18 single-organism, Gram-negative infections. The overall cure rate was 54%. The most common infection was pneumonia (47% responded to treatment). Eighty precent of the cases of septicemia were cured. The most common infecting organism was Klebsiella pneumoniae (45% with this infection responded). Eight cases of infection of unknown origin occurred (63% responded to treatment). Overall, 47% of the patients whose neutrophil count remained unchanged or decreased responded, while 61% of those whose neutrophil count remained unchanged or increased responded. There was no close correlation between the minimum inhibitory concentrations and the clinical responses. Sulfamethoxazole-trimethoprim orally is a well tolerated and effective form of antimicrobial therapy.