Early secondary brain abscess formation caused by Bacteroides fragilis at the intracerebral hemorrhage site: A case report.

BACKGROUND: Brain abscess formation at the site of intracerebral hemorrhage (ICH) is extremely rare, particularly in association with anaerobic pathogens, such as Bacteroides fragilis, and its pathogenesis remains incompletely understood. Here, we report an ultimately fatal case of a brain abscess caused by this organism that developed at an ICH site. CASE DESCRIPTION: An 86-year-old woman presented with right parieto-occipital ICH accompanied by systemic inflammatory signs. Abdominal computed tomography performed at admission revealed findings consistent with sigmoid diverticulitis. Despite initial conservative management, the patient developed bacterial meningitis due to B. fragilis. Sixteen days after stroke onset, she experienced rapid neurological deterioration caused by massive perilesional edema. Emergency surgery revealed purulent material within the hematoma cavity, and cultures confirmed B. fragilis, establishing a diagnosis of secondary abscess formation at the ICH site. Although surgical intervention and targeted antimicrobial therapy were initiated, the patient developed cerebritis and ventriculitis and ultimately died. CONCLUSION: This case suggests that hematogenous dissemination from an intra-abdominal infection may seed injured brain tissue in the early phase after hemorrhage. Disruption of the blood-brain barrier and the relatively avascular, anaerobic environment of a hematoma may predispose patients to abscess formation. In patients with ICH, persistent fever and progressive neurological deterioration despite antimicrobial therapy should prompt consideration of contrast-enhanced neuroimaging to evaluate possible intracranial infectious complications.