Myelosuppression associated with co-trimoxazole as a prophylactic antibiotic in the maintenance phase of childhood acute lymphocytic leukemia.

Thirty-seven children with acute lymphocytic leukemia in clinical remission for at least 6 months completed a 1-year trial in which they were randomly assigned in a double-blind fashion to receive co-trimoxazole twice daily for 6 months followed by placebo for 6 months (18 patients) or placebo followed by co-trimoxazole (19 patients). Total amounts of maintenance chemotherapy administered during both periods were similar. During administration of co-trimoxazole significant reductions were documented in the patients' average total white blood count (P less than 0.001), absolute neutrophil count (P less than 0.001), absolute lymphocyte count (P = 0.009), and platelet count (P = 0.002) compared with values obtained during the placebo period. Patients had on the average 1.6 infections during the co-trimoxazole period compared with 2.5 infections during placebo administration (P = 0.008). It is concluded that, although co-trimoxazole is an effective prophylactic antibiotic in children with acute lymphocytic leukemia, the resultant myelosuppression could potentially hamper the administration of maintenance cancer chemotherapy.