Hyperammonemia caused by urinary tract infection due to Corynebacterium urealyticum

Hyperammonemia can cause disturbances in consciousness. Although it is commonly associated with advanced liver disease, there have also been reports of hyperammonemia induced by obstructive urinary tract infections due to urease-producing bacteria. In this report, we present the case of an 87-year-old man with acutely impaired consciousness due to hyperammonemia resulting from an obstructive urinary tract infection caused by Corynebacterium urealyticum. The patient was admitted with a 1-day history of fever and impaired consciousness. Gram staining of the urine revealed gram-positive bacilli and white blood cells, and the pH test result was alkaline. Computed tomography revealed a dilated bladder with a large amount of urine and contrast enhancement of the bladder wall. Plasma ammonia levels were elevated. Therefore, urinary catheterization and vancomycin administration were initiated. The following day, the plasma ammonia level normalized, and the patient's level of consciousness returned to normal. Urine culture revealed the growth of C. urealyticum. Accordingly, the patient was diagnosed with an obstructive urinary tract infection caused by C. urealyticum, which presumably caused hyperammonemia and acutely impaired consciousness.