Trimethoprim-sulfamethoxazole salvage for refractory listeriosis during maintenance chemotherapy for acute lymphoblastic leukemia

A 5-year-old boy with acute lymphoblastic leukemia (ALL) and intolerance to oral trimethoprim-sulfamethoxazole (TMP/SMX) had Listeria monocytogenes ba cteremia and meningitis develop during maintenance chemotherapy. Despite pr ompt administration of IV amoxicillin/gentamicin and microbiologic clearanc e of the bloodstream, the patient had no response to therapy after a course of 7 days. Intravenous TMP/SMX (10 mg/kg per day of TMP) was added to the antibiotic regimen after desensitization. Fever and meningeal signs rapidly resolved? and the patient was ultimately cured. Amoxicillin and gentamicin , although highly active and synergistic in vitro against L. monocytogenes, have limited intracellular penetration and activity. In contrast, TMP/SMX has bactericidal extracellular and intracellular activity against Listeria and excellent central nervous system penetration, and thus may be effective for the treatment of refractory listeriosis.