Sulfamethoxazole stone in a patient with extensive history of urolithiasis and recurrent urinary tract infections.

Although rare, sulfamethoxazole-induced urolithiasis has been reported in patients taking trimethoprim-sulfamethoxazole (TMP/SMX). We present the case of a 79-year-old female who formed sulfamethoxazole stones in the setting of chronic indwelling catheterization with recurrent urinary tract infections (UTIs). The patient was a recurrent stone former with five prior stone composition analyses over a 10-year period varying from calcium phosphate to calcium oxalate, to struvite. We highlight the need for further investigation of this phenomenon given the frequent use of TMP/SMX in stone formers with recurrent infections.