TRIMETHOPRIM-SULFAMETHOXAZOLE PROPHYLAXIS IN GRANULOCYTOPENIC PATIENTS WITH ACUTE-LEUKEMIA - EVALUATION OF SERUM ANTIBIOTIC LEVELS IN A RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED DEPARTMENT-OF-VETERANS-AFFAIRS COOPERATIVE STUDY

Despite widespread use of trimethoprim-sulfamethoxazole (TMP-SMZ) for prophylaxis in neutropenic patients, questions remain regarding its ef ficacy, toxicity, the risk of selection of resistant isolates, and the relation of its activity to selective decolonization vs. the attainme nt of direct inhibitory levels within blood and tissues. We evaluated the effect of TMP-SMZ (160/800 mg orally every 12 hours) in 42 adult g ranulocytopenic patients (<100 absolute neutrophils/mm3, mean duration 13.3 days) undergoing chemotherapy for acute leukemia at 11 participa ting Veterans Administration Medical Centers in a randomized, double-b lind, placebo-controlled trial. No significant differences in survival , frequency of bacteremia, overall infections, use of systemic antimic robial therapy, or adverse effects, including myelosuppression, were o bserved between patients receiving TMP-SMZ vs. those receiving placebo . All patients acquired trimethoprim-resistant organisms. Concentratio ns of trimethoprim in serum were significantly lower before febrile ep isodes than when patients were afebrile. These results suggest that th e purported activity of TMP-SMZ may be related to the serum concentrat ion achieved. Moreover, the results highlight the need for additional study of the value of antibiotic prophylaxis in neutropenic patients.