Propionibacterium Acnes Brain Abscess in an Immunocompetent Man in the Absence of Prior Neurosurgery.

Propionibacterium acnes is a rare, but established, cause of intracranial abscesses. We describe a case of P. acnes brain abscess in an immunocompetent man without prior neurosurgery. A 49-year old man with mild psoriasis presented with a two-week history of gait changes, generalized weakness and a two-day history of headaches, aphasia and confusion. Imaging revealed a left thalamic mass and surgical biopsy suggested a pyogenic abscess. Cultures of biopsy samples of the abscess grew P. acnes alone. MRI and serial neurological exam showed marked clinical improvement with intravenous antibiotics. The significant reduction in the abscess was sustained on MRI obtained at six weeks after completion of antibiotic therapy. In conclusion, P. acnes must be considered as a differential diagnosis in individuals presenting with features suggestive of a brain abscess even in the absence of immunosuppression or previous neurosurgery.