Fusobacterium species are anaerobic gram-negative bacilli typically associated with head and neck infections and anaerobic septicemia. Central nervous system (CNS) involvement is rare and most often results from contiguous extension or hematogenous spread during systemic infection. We report a case of multifocal intracranial abscesses after incomplete treatment of Fusobacterium bacteremia in an immunocompetent patient without an identifiable head, neck, or dental source.
A 19-year-old male with a remote gunshot wound to the left hip presented with two weeks of progressive headache and visual blurring after recent hospitalization for a first-time seizure. During that admission, he was septic with Fusobacterium bacteremia and discharged on a 14-day course of oral metronidazole, which he completed for only three days.
On presentation, he was afebrile and neurologically intact aside from headache. Labs showed WBC 7.9 × 10⁹/L, platelets 680 × 10⁹/L, CRP 15 mg/L, and ESR 47 mm/h. Head CT revealed multiple right-hemispheric lesions with vasogenic edema and 4 mm midline shift; MRI demonstrated multiple ring-enhancing supratentorial abscesses, largest in the right parietal and parieto-occipital regions.
He received empiric vancomycin, cefepime, and metronidazole, followed by right parietal craniotomy with evacuation of purulent material; cultures remained sterile. CT of the head and neck soft tissues, chest, abdomen, and pelvis revealed no local source of infection. Transthoracic and transesophageal echocardiography showed no vegetations or evidence of endocarditis. Diagnostic studies were negative for co-infection, including HIV, and showed no evidence of immunocompromise.
He was discharged at his neurologic baseline with symptom resolution, on a three-week course of IV ceftriaxone and oral metronidazole, with outpatient follow-up.
This case describes a rare hematogenous Fusobacterium infection in an immunocompetent patient, presenting with multifocal brain abscesses and no contiguous source. The absence of typical predisposing factors, including head or neck infection, trauma, or instrumentation, makes this presentation particularly uncommon.