Abstract
Lactococcus lactis cremoris (L. lactis cremoris) infections are very rare in humans. Only three case reports of brain abscess have been reported and the infectious routes and pathological features are still unknown. We experienced a subdural empyema due to L. lactis cremoris in an immunocompetent adult. A 33-year-old man was admitted with fever, right facial pain, left hemiparesis, and left hemianopsia. Computed tomography demonstrated low density fluid collection in the right falcotentorial subdural space. Magnetic resonance (MR) images revealed a high signal lesion on a diffusion-weighted image (DWI) and fluid attenuated inversion recovery (FLAIR) images in the right paratentorial and parafalcine subdural space, right maxillary sinus, and bilateral ethmoidal sinus. He underwent two sequential open surgeries for removal and drainage of empyema and was treated with antibiotics including meropenem and ampicillin. To our knowledge, this is the first report of subdural empyema caused by L. lactis cremoris infection. We report the case and discuss the pathological features with the previous literature.