Secondary brain abscess following simple renal cyst infection: a case report

BACKGROUND: Escherichia coli (E. coli) is the most common causative bacteria of neonatal meningitis, but hematogenous intracranial E. coli infection is rare in adults. Moreover, intracranial abscess formation owing to E. coli, including brain abscesses and subdural empyema formation, is extremely rare. We herein present a case involving a patient with a brain abscess owing to E. coli following a simple renal cyst infection. A review of the literature is also presented. CASE PRESENTATION: A 77-year-old Japanese woman with a history of polymyalgia rheumatica was admitted to our hospital because of persistent fever, right flank pain, and pyuria. Intravenous antibiotics were administered; however, her level of consciousness deteriorated 6 days after admission. Contrast-enhanced magnetic resonance imaging showed a brain abscess in the left occipital lobe and pyogenic ventriculitis. Enhanced abdominal computed tomography revealed a right renal cyst with heterogeneous content. Culture of urine, blood, and aspirated pus from the infected cyst revealed E. coli with identical antibiotic sensitivity in all sites, suggesting that the cyst infection and subsequent bacteremia might have caused the brain abscess. The patient recovered after a 6-week course of meropenem. CONCLUSION: The prognosis of patients with E. coli-associated intracranial abscess is usually poor. Advanced age and immunosuppression may be potent risk factors for intracranial abscess formation owing to the hematogenous spread of E. coli.