Abstract Background and Aims Urinary tract infection (UTI) caused by urease-producing bacteria is an uncommon but important cause of hyperammonaemia leading to cerebral injury. Severe manifestations comprise seizures, encephalopathy, coma, and death. Common pathogens include Proteus, Morganella, Klebsiella, Staphylococcus, and Corynebacterium species. Corynebacterium spp., however, are slow-growing and may be overlooked in routine cultures. This review synthesizes 20 reported cases, highlighting diagnostic challenges and clinical outcomes. Methods A scoping review was conducted according to PRISMA-ScR guidelines. Multiple academic databases were searched for case reports describing species-level identification of coryneform bacteria as the primary cause of UTI-associated hyperammonaemia. Of 1,151 records screened, 19 publications (20 patients) met inclusion criteria after full-text review. Results Between 1991 and June 2025, 20 cases of hyperammonaemia secondary to urease-producing Corynebacterium UTIs were identified after exclusion of alternative aetiologies. Patients (mean age 71.9 years; female-to-male ratio 3:2) frequently had neurological or urological comorbidities and presented with urinary obstruction and moderate-to-severe coma. Ammonia concentrations were markedly elevated (mean 341.5 μg/dL), and urine pH was consistently alkaline. Corynebacterium urealyticum accounted for 80% of cases, followed by C. pseudodiphtheriticum and C. riegelii. All patients survived with supportive care, urinary decompression, and targeted antimicrobial therapy. C. urealyticum often required glycopeptides due to multidrug resistance. Conclusions Hyperammonaemia caused by slow-growing, urease-producing Corynebacterium spp. is a diagnostic challenge and may result in life-threatening neurological complications if unrecognized. Prolonged urine culture incubation and careful integration of clinical findings with urinalysis (alkaline pH, leukocyturia) are essential for timely diagnosis and appropriate treatment.
Soriano et al. (Mon,) studied this question.