Oligella urethralis bacteremia associated with urinary tract obstruction: A case report and literature review

Oligella urethralis is a gram-negative, non-fermentative coccobacillus that is considered part of the normal urogenital flora but can cause opportunistic infections in immunocompromised patients or those with underlying conditions. Coccobacilli such as O. urethralis are rarely encountered as urinary pathogens compared to typical rod-shaped bacteria, making their identification clinically significant. We report a case of O. urethralis bacteremia in a 74-year-old male long-term care facility resident with ureteral stones who presented with acute pyelonephritis and bacteremia. Blood and urine cultures both yielded small gram-negative bacilli, which were identified as O. urethralis using MALDI-TOF mass spectrometry, and the patient was successfully treated with antibiotics. A literature search for reports published between 1987 and May 2025 identified six previously reported cases of O. urethralis bacteremia with English abstracts. Including our case, a total of seven cases were analyzed. All cases occurred in elderly patients (median age 79 years) with predisposing conditions, particularly obstructive uropathy. The prognosis was favorable; only one death occurred among the seven patients (1/7), and it was attributed to causes other than the O. urethralis infection. O. urethralis should be considered a potential pathogen in elderly patients with obstructive uropathy presenting with bacteremia, especially when gram-negative coccobacilli are identified on blood cultures. Fluoroquinolone resistance is frequently reported in O. urethralis, and awareness of this organism is important for appropriate antimicrobial selection, particularly given the challenges in antimicrobial susceptibility interpretation due to lack of species-specific breakpoints.