Vol.74 No.5 September 2026

A case of hyperammonemia associated with Corynebacterium urealyticum urinary tract infection and urinary dysfunction

Ichie Akahoshi¹⁾ and Yasutaka Tohyama¹⁾

¹⁾Department of Pharmacy, Oita Oka Hospital, 3-7-11 Nishitsurusaki, Oita City, Oita, Japan

Abstract

We report a case of hyperammonemia in a 78-year-old woman who was transported to the emergency department due to impaired consciousness. Laboratory tests revealed a blood ammonia level of 146 μg/dL, and the patient was admitted to the hospital. Clinical examinations revealed no evidence of hepatic disease, portosystemic shunt, or cerebrovascular disorder. Urine culture grew gram-positive rods resembling Corynebacterium, prompting the initiation of vancomycin (VCM) for suspected obstructive urinary tract infection caused by urease-producing bacteria. The patient had been taking paroxetine 15 mg daily for Parkinson's disease-related depression, and had been initiated on mirabegron 50 mg three months earlier to address nocturia. As both agents increase the risk of urinary retention, they were discontinued after admission. Her level of consciousness improved in parallel with the reduction in the blood ammonia level, and VCM administration was discontinued after eight days. The isolated organism was identified as Corynebacterium urealyticum.
In this case, urinary retention caused by mirabegron and delayed metabolism of paroxetine due to CYP2D6 inhibition may have contributed to the aggravation of urinary dysfunction. In patients with underlying diseases associated with voiding dysfunction or drug-induced voiding dysfunction, the development of obstructive urinary tract infection caused by urease-producing bacteria may exacerbate hyperammonemia. Therefore, withdrawal of the causative agents, relief of urinary retention, and appropriate antimicrobial therapy are considered useful.

Key word

hyperammonemia, urease-producing bacteria, urinary tract infection, drug-induced urinary dysfunction, drug interaction

Received

February 5, 2026

Accepted

May 25, 2026

Jpn. J. Chemother. 74 (5): 556-562, 2026