A Rare Case of Hyperammonemia Caused by Urinary Tract Infection Due to Corynebacterium riegelii

Hyperammonemia is a crucial differential diagnosis leading to consciousness disorders. While it is often associated with liver failure in most cases, it is imperative to be aware that hyperammonemia can also be induced by rare urease-producing bacteria, such as Corynebacterium riegelii causing obstructive urinary tract infections, as seen in this case. We report the case of an 85-year-old woman with no history of liver dysfunction and no previous indications of voiding difficulties. Based on the symptoms of consciousness impairment, elevated ammonia (NH₃) levels in blood tests, and CT and urine findings, the diagnosis was obstructive uropathy due to urease-producing bacteria. Subsequent urine culture detected Corynebacterium riegelii, a urease-producing bacterium with limited reported cases. Treatment involved bladder catheterization and antibiotic administration, leading to a rapid improvement in consciousness. Given that this case, where voiding difficulties have not been previously diagnosed, exists, addressing voiding dysfunction is also crucial.