An 87-year-old woman diagnosed with dementia with Lewy bodies (DLB) 2 years earlier was referred to our institution because of difficulty walking. She was diagnosed with urinary tract infection and admitted to our hospital. During hospitalisation, she became delirious, which prompted the administration of haloperidol. Afterwards, an altered level of consciousness was noted, measuring 300 on the Japan coma scale. A blood test revealed hyperammonaemia without liver damage. Urine culture detected the presence of Corynebacterium urealyticum. Therefore, we diagnosed this case as one of hyperammonaemia due to urinary tract infection caused by urease-producing bacteria. Soon after the insertion of a urethral catheter, the ammonia level decreased, and the consciousness level improved. In this case, the patient took medication to preserve her bladder function, which is frequently associated with DLB. We suspected that the drug caused urinary retention, resulting in hyperammonaemia. Hyperammonaemia due to these bacteria should be considered in DLB patients with an impaired consciousness, especially in those using regulators of the urinary bladder function.
Keywords: Consciousness disturbance; Dementia with Lewy bodies; Hyperammonemia; Urease-producing bacteria; Urinary tract infection.