Rare Case of Thalamic Abscess Due to Listeria Monocytogenes

Introduction

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Listeria monocytogenes (L. monocytogenes) is a Gram-positive, facultatively anaerobic, non-spore-forming bacillus. In most cases, it is a contaminant in food and water [1,2], and ingestion is the most common route of transmission. It is an uncommon cause of invasive foodborne infection in humans, with an estimated 1600 cases per year in the United States [3,4]. However, the link between neurological presentation and the ingestion of food or water contaminated by listeria may be difficult to identify, as the onset of symptoms can be as late as 1 month after pathogen exposure [4]. Immunodeficiency, extreme age (neonates and people older than 50 years of age), and pregnancy are correlated with a higher risk of invasive infection. Meningoencephalitis is the most common central nervous system (CNS) manifestation of listeriosis. However, brain abscess contributes only 1–10% of all CNS listeriosis [5,6]. The disease carries significant morbidity and mortality rates. There is no specific radiologic characteristic that can be observed in a radiograph, but the most common manifestation is ring-enhancing lesions, as seen with other types of brain abscesses. Early diagnosis followed by prompt and appropriate antibiotic therapy improves clinical prognosis.

Case Presentation

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Here, we report the case of a 71-year-old female with a recently diagnosed anal squamous cell carcinoma in August 2020. She completed chemotherapy and radiation therapy in October 2020. She also had a history of liver transplant 17 years prior due to primary biliary cirrhosis. Initially, the patient presented to an emergency room with a fever of 103 F, nausea, and myalgia. Blood cultures were drawn. Computed tomography of the abdomen and pelvis showed a 1.8 ˆ 1.5 cm soft tissue prominence in the perirectal space, which was thought to represent either phlegmonous change or the previously diagnosed anal carcinoma. She was discharged on oral Augmentin for possible intraabdominal infection. Three days later, the patient again presented to an emergency room, this time with a worsening mental status over two days. The physical exam revealed cachexia, stupor, brief opening of the eyes to physical stimuli, and strength in all four extremities. There was no neck stiffness in this patient. Blood culture from the ER visit three days prior was positive for Gram-positive rods and grew L. monocytogenes [Figure 1]. Routine laboratory findings, including complete blood count, and renal and hepatic functions, were all within normal limits. She underwent lumbar puncture, which showed markedly elevated protein at 1000, normal glucose, and increased nucleated cells, with lymphocytic pleocytosis, which is typical in CNS listeriosis. MRI of the brain revealed a single small 5–6 mm round ring-enhancing lesion in the right thalamus and surrounding edema (Figure 2). The patient received three weeks of synergistic therapy with ampicillin and gentamicin. She completed a total of six weeks of ampicillin and two weeks of gentamicin synergy with neurological improvement. Figure 1: Stasis Dermatitis. Figure 2: MRI brain demonstrated single ring-enhancing lesion in right thalamus.

Discussion

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Listeria brain abscesses are extremely rare and were reported in only 56 cases in the world from 1968 to 2011 [7]. The most common form of listeria CNS infection is meningoencephalitis. Brain abscess occurred in only a small percentage of all listeria CNS infections, and the common locations were the thalamus, pons, and medulla [8]. Hematogenous spread is the main route of infection [6]. L. monocytogenes is ubiquitously found in soil and water. Humans are infected by this organism via the ingestion of contaminated packaged food, especially seafood, dairy, and vegetables. Pathogenesis invades the small bowel and accumulates in mesenteric lymph nodes and the bloodstream. When it penetrates the blood–brain barrier, it can cause CNS manifestations of the disease. A predisposing factor which can cause severe infections in humans is an immunocompromised status [6]. Our patients advanced age and her prior history of cancer represent two well-established risk factors for invasive listeriosis. Our patient presented with indolent symptoms, such as fever and altered sensorium, which perhaps delayed diagnosis. Additionally, her listeria infection might have been partially treated by the oral Augmentin, and hence, the course of the disease was prolonged. The common etiologies responsible for brain abscesses are Staphylococcus and Streptococcus, with frequent intracranial locations being the frontal–temporal, frontal–parietal, parietal, cerebellar, and occipital lobes. The most common organisms responsible for thalamic abscesses are Streptococcus species and anaerobic organisms [9]. Our patient had a brain abscess in the thalamic region, which is an unusual location.

References

1. 1. Johnson, J.E.; Mylonakis, E. Listeria monocytogenes. In Principles and Practice of Infectious Diseases, 9th ed.; Bennett, J.E., Dolin, R., Blaser, M.J., Eds.; Elsevier: Amsterdam, The Netherlands, 2019; p. 2543.
   2.  Bille, J. Listeria and Erysipelothrix. In Manual of Clinical Microbiology, 9th ed.; ASM Press: Washington, DC, USA, 2007; p. 474.
   3. Scallan, E.; Hoekstra, R.M.; Angulo, F.J.; Tauxe, R.V.; Widdowson, M.A.; Roy, S.L.; Jones, J.L.; Griffin, P.M. Foodborne illness acquired in the United States—Major pathogens. Emerg. Infect. Dis. 2011, 17, 7–15. [CrossRef] [PubMed]
   4.  DeJesus-Alvelo, I.; Merenda, A. A Case Report of Listeria monocytogenes Abscesses Presenting as Cortically Predominant Ring-Enhancing Lesions. Case Rep. Neurol. 2015, 7, 105–109. [CrossRef] [PubMed]
   5.  Castro, A.; Hernández, O.H.; Uribe, C.S.; Guerra, A.; Urueña, P. Brainstem encephalitis and myelitis due to Listeria monocytogenes: A case report and literature review. Biomedica 2013, 33, 343–349. [CrossRef] [PubMed]
   6.  Sakarunchai, I.; Saeheng, S.; Oearsakul, T.; Sanghan, N. Listeria monocytogenes brain abscess on MR imaging mimicking the track of a migrating worm like a sparganum: A case report. Interdiscip. Neurosurg. 2016, 5, 9–11. [CrossRef]
   7.  Cone, L.A.; Leung, M.M.; Byrd, R.G.; Annunziata, G.M.; Lam, R.Y.; Herman, B.K. Multiple cerebral abscesses because of Listeria monocytogenes: Three case reports and a literature review of supratentorial listeria brain abscess(es). Surg. Neurol. 2003, 59, 320–328. [CrossRef]
   8.  Limmahakhun, S.; Chayakulkeeree, M. Listeria monocytogenes brain abscess: Two cases and review of the literature. Southeast Asian J. Trop. Med. Public Health 2013, 44, 468–478. [PubMed]
   9. enol, Ö.; Süslü, H.T.; Tatarl, N.; Tiryaki, M.; Güçlü, B. Thalamic abscess caused by a rare pathogen: Streptococcus constellatus. Pan African Med. J. 2016, 24. [CrossRef] [PubMed]

Figure 1:

Blood culture gram stain: Gram positive bacilli.

Figure 2:

MRI brain demonstrated single ring-enhancing lesion in right thalamus.