Failure of Oral Trimethoprim-Sulfamethoxazole Prophylaxis in Acute Leukemia

Abstract

Several recent studies of patients with granulocytopenia have shown that the prophylactic administration of oral trimethoprim–sulfamethoxazole (TMP-SMX) is effective in preventing sepsis with Enterobacteriaceae.^{1 2 3 4 5} However, we have recently seen two patients with acute leukemia and granulocytopenia who received oral TMP-SMX prophylaxis but subsequently had sepsis with Enterobacteriaceae that were resistant to TMP-SMX. In one patient, a transferable plasmid encoding resistance to trimethoprim and sulfonamide was isolated from two different bacterial species. In the other patient, a transferable sulfonamide-resistance plasmid was found together with chromosomally mediated trimethoprim resistance in a single strain.MethodsPatients and Bacterial StrainsThe TMP-SMX-resistant strains were . . .