Rationale: Listeria monocytogenes rarely affects immunocompetent adults, and only a few cases of encephalitis caused by L monocytogenes in humans have been reported in China.
Patient concerns: A 37-year-old male patient presented with headache and fever of 38°C to 39°C for 2 days and dysphoria and dystrophy for 1 day.
Diagnosis: The patient was diagnosed as having encephalitis, and his cerebrospinal fluid (CSF) and blood cultures tested positive for L monocytogenes.
Interventions: The patient was treated with intravenous vancomycin, meropenem, mannitol, methylprednisolone, and enteral nutrition. The computed tomography (CT) scan showed swelling of the brain and hydrocephalus. The patient was treated with emergent surgery, a ventricular drainage tube was inserted, and the CSF was drained daily.
Outcomes: Despite adequate therapy, the illness was severe and progressed rapidly. The patient died 2 weeks after admission.
Lessons: We report a rare case of L monocytogenes encephalitis in a previously healthy immunocompetent adult in China. The patient's CT scans showed increasing brain swelling and hydrocephalus, and the patient's condition progressively deteriorated.