Listeria monocytogenes Brain Abscess Presenting With Stroke-Like Symptoms: A Case Report

Abstract

We present a case of Listeria monocytogenes brain abscess in an immunocompromised patient admitted for stroke-like symptoms of headache and aphasia. Computerized tomography of the head revealed a 1.7 x 1.3 cm left frontal lobe lesion with surrounding edema, secondary to stroke, tumor, or abscess. Magnetic resonance imaging brain revealed a ring-enhancing lesion and a small contralateral area of restricted diffusion. Two of the two blood cultures grew an organism identified as L. monocytogenes using matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Treatment with ampicillin and trimethoprim-sulfa yielded marked symptomatic improvement. A brain biopsy was consistent with bacterial abscess. The patient's clinical course was favorable, with improved aphasia and negative follow-up blood cultures. A literature review found a limited number of L. monocytogenes abscess cases and none had clear guidelines for diagnosis. Recent studies have proposed five criteria for diagnosis. Our patient fulfilled three of these proposed guidelines.

Keywords: brain abscess; case report; diagnosis; listeria; treatment.

Figure 1. Axial and coronal CT head and MRI revealing left intra-axial frontal lobe lesion with edema

Panel A: axial CT head without contrast, panel B: coronal CT head without contrast, revealing a left intra-axial frontal lobe lesion measuring 1.7 x 1.3 cm with surrounding edema (arrow), panel C: axial MRI brain with contrast, and panel D: coronal cuts revealing an intra-axial peripherally enhancing lesion centered in the medial posterior left frontal lobe surrounded by vasogenic edema with some areas of tubular appearance measuring 1.6 x 1.9 x 2.2 cm (arrow) with minimal mass effect and no midline shift.

Figure 2. MRI brain findings

MRI brain with contrast, axial cuts. Panel A: diffusion-weighted imaging (DWI), panel B: apparent diffusion coefficient (ADC) revealing scattered areas of diffusion restriction (arrow) in the center of the left frontal lesion, panel C: additional small punctiform area of diffusion restriction in the right frontal lobe (arrow), and panel D: corresponding ADC (arrow) concerning acute infarcts from an embolic source. Not presented, however there was no evidence of blood products on the susceptibility images.

Figure 3. Surgical pathology histologic examination

Surgical pathology - magnification 100 oil: histologic examination reveals abscess associated with reactive gliosis, microhemorrhage, and very focal perivascular lymphocytosis. No morphologic evidence of glioma, metastatic carcinoma, lymphoma, granulomatous inflammation, or viral cytopathic effect.