To report a case of Listeria brain abscess that was initially misdiagnosed as acute left middle cerebral artery (MCA) stroke

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An 87 year old male with liver cancer and chronic lymphocytic leukemia presented with acute onset dysarthria, right hand weakness, and right facial focal aware seizures. Initial CT/CTA was interpreted as an acute left anterior parietal infarct with decreased filling of distal left MCA branches in the infarcted region. Over the course of several days, his speech worsened and became apraxic, which was attributed to stroke expansion. An MRI brain was recommended, but the patient was unable to tolerate the study and was discharged to acute rehab. He re-presented 1 day later due to progression of symptoms to aphasia, right hemispatial neglect, and right hemiparesis. CT head was interpreted as evolution of subacute stroke with increased mass effect. MRI brain under generalized anesthesia showed a left parietal ring enhancing lesion with restricted diffusion and surrounding vasogenic edema, most concerning for cerebral abscess or malignancy. Blood cultures returned positive for Listeria monocytogenes. He received a long course of intravenous ampicillin therapy. A repeat MRI one month later demonstrated reduction in the size of the ring enhancing lesion and decreased vasogenic edema, and his neurological symptoms had resolved at follow-up.

Our case demonstrates a rare occurrence of Listeria monocytogenes brain abscess manifesting as a worsening left MCA syndrome. There have been other case reports of Listeria causing brain abscesses that mimic stroke syndromes or meningoencephalitis, particularly in patient populations that carried a known malignancy or hematological diagnosis or were on immunosuppressants. CNS infection and specifically Listeria should be considered in these populations as an alternative etiology when symptoms continue to progress despite initial management.