An immunocompetent patient with culture-negative multiple brain abscesses caused by Fusobacterium nucleatum.

The diagnosis and treatment of brain abscesses have advanced due to the utilization of modern microbiological and neurosurgical methods. Here we present a 49-year-old female patient presented with headache and neurological symptoms. Initial evaluation revealed multiple ring-enhanced brain lesions and a lung cavitary lesion initially suspected to represent a malignant process. Stereotactic aspiration provided the diagnosis of brain abscesses but yielded negative cultures. 16S ribosomal RNA analysis enabled the identification of Fusobacterium nucleatum. For ten weeks, the patient was treated with ceftriaxone and metronidazole. A marked clinical and radiological improvement was noted. Brain abscess is a severe intracranial infectious process with significant morbidity and mortality. Microbiological analysis is challenging due to the location of the infection, the broad spectrum of causative agents, and the low yield of cultures. Fusobacterium nucleatum is an anaerobic bacteria with a tendency to abscess formation and is isolated from 2% of brain abscesses. The utilization of 16S RNA analysis improves microbiological identification rates in brain abscesses, as in other infectious entities, enabling better pathogen characterization and more suitable treatment.