Haemolytic anaemia and renal failure associated with antibodies to trimethoprim and sulfamethoxazole.

Aim: The aim of this study was to support a clinical diagnosis of drug-induced immune haemolytic anaemia (DIIHA). Background: DIIHA is rare and has only been described twice with the antibiotic combination of trimethoprim (TMP) and sulfamethoxazole (SMX). Methods/Materials: Serologic tests for drug antibodies were performed using methods previously published by our laboratory. Results: A 44-year-old woman experienced body aches, chills, chest pressure, nausea and a rash while receiving TMP–SMX; a week later her haemoglobin was low and she was in renal failure. At the hospital, the direct antiglobulin test (DAT) was positive (C3 only) and the serum reacted with all red blood cells (RBCs) by the gel method only (TMP–SMX is present in the RBC diluent used for the gel method). At the Red Cross immunohaematology laboratory, the patient's serum was reactive in the presence of TMP–SMX (haemolysis and positive antiglobulin test), pure TMP (positive antiglobulin test using anti-IgG only) and pure SMX (haemolysis and positive antiglobulin test using both anti-IgG and anti-C3). The patient was treated with transfusions and haemodialysis and was discharged after a week in stable condition. Conclusion: We describe a patient who appeared to have haemolytic anaemia and renal failure associated with antibodies to both TMP and SMX.