Nephrolithiasis Associated with Sulfadiazine Therapy in an Infant with Congenital Toxoplasmosis: A Case Report

Objectives To describe a rare case of sulfadiazine-associated nephrolithiasis in an infant treated for congenital toxoplasmosis and to highlight the clinical implications for monitoring and management during prolonged therapy. Methods We report a case of an 11-month-old male infant diagnosed with congenital toxoplasmosis who developed bilateral nephrolithiasis (maximal size approximately 1.2 cm) and hydronephrosis after 9 months of continuous treatment with sulfadiazine, pyrimethamine, and folinic acid. Six days prior to admission, the infant presented with fever, hematuria, leukocyturia, and renal dysfunction. Results Following discontinuation of sulfadiazine and administration of intravenous antibiotics and supportive care, renal function normalized and the stones resolved. Conclusions This case underscores the potential for severe urological adverse effects associated with sulfadiazine therapy in infants. Close monitoring of renal function and urinary ultrasound should be undertaken during prolonged sulfadiazine therapy, particularly in regions with limited clinical experience with the drug.