Encrusted pyelitis and hyperammonemia due to Corynebacterium urealyticum in a kidney transplant recipient

Introduction: The bacterium Corynebacterium urealyticum produces urease and can cause encrusted pyelitis, a condition characterized by calcifications of the renal pelvis and ureteral wall, which may obstruct the urinary tract. We describe a case of encrusted pyelitis caused by C. urealyticum in a kidney transplant patient presenting with altered consciousness due to hyperammonemia. Case presentation: An 81-year-old woman with a history of cadaveric kidney transplantation, thirty years prior, presented with acute altered consciousness during hospitalization. Laboratory findings showed acute renal failure and hyperammonemia, and urinalysis revealed high pH (>9.0) and pyuria. Abdominal non-contrast computed tomography revealed calcification of the renal pelvis and hydronephrosis. C. urealyticum was isolated from both blood and urine cultures. A diagnosis of encrusted pyelitis and hyperammonemia caused by C. urealyticum was made, and intravenous vancomycin was administered. Following the initiation of vancomycin and the temporary hemodialysis, her hyperammonemia and altered consciousness rapidly improved. Treatment with vancomycin resulted in a reduction of the urinary tract encrustation. Conclusion: This case highlights C. urealyticum as a urinary pathogen that can lead to encrusted pyelitis, hyperammonemia, and altered consciousness in renal transplant patients.