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Updated: Jun 22, 2026

Listeria monocytogenes Infection of the Brain
Published on: October 2, 2018
Listeria meningoencephalitis in an immunocompetent person
Alija Drnda1, Nada Koluder, Amir Hadzic
1Clinic for Infectious Diseases, University Clinical Center of Sarajevo, BiH.
Abstract:
Listeria monocytogenes is a small, aerobic or facultative anaerobic, non-sporulating gram positive bacillus that can be isolated from soil, vegetation or animal reservoirs. There are six species of Listeria, and only L. monocytogenes is pathogenic for humans. Human disease occurs mainly in immunocompromised people, neonates and in pregnancy, while the cases in immunocompetent people are rare. CNS manifestations of the disease can be in form of meningitis, encephalitis, and also cerebritis and abscess since L. monocytogenes shows tropism for brain and brain stem as well for the meninges. In this case we presented 55 year old male patient with etiologically confirmed listerial meningoencephalitis, transferred from regional hospital tothe Clinic for Infectious Diseases with diagnosis of acute meningoencephalitis. Disease started 4 days before the admission. Prior to this the patient was completely healthy. In his history he denied any preexisting disease. At admittance he was febrile, with altered consciousness, disoriented, showing ocular deviation, dystaxia, and with completely positive meningeal signs. Neurologist diagnosis was rhombencephalitis. CSF analysis showed mildly opalescent liquor with pleocytosis 546/mm3 and polymorphonuclear cell predominance >70%. CSF culture showed positive isolate of L. monocytogenes. Initial therapy was: Penicillin G and Chloramphenicol, together with all other supportive and symptomatic therapy. After initial therapy and based on antibiogram, ampicillin was administered for4 weeks, followed by imipenemum for 10 days. Control CSF analysis showed pleocytosis and increased protein level and the patient was discharged as recovered with diagnosis of acute meningoencephalitis
Insights
This case study highlights a rare instance of Listeria monocytogenes causing meningoencephalitis in an immunocompetent adult. Prompt diagnosis and appropriate antibiotic treatment led to the patient's recovery.
Area of Science:
- Neuroscience
- Infectious Diseases
- Microbiology
Background:
- Listeria monocytogenes is a bacterium found in soil and animal reservoirs, pathogenic to humans, particularly affecting immunocompromised individuals, neonates, and pregnant women.
- Central nervous system (CNS) involvement, including meningitis, encephalitis, cerebritis, and abscess, can occur due to L. monocytogenes' tropism for the brain and meninges.
Observation:
- A 55-year-old previously healthy male presented with acute meningoencephalitis, characterized by fever, altered consciousness, disorientation, ocular deviation, dystaxia, and positive meningeal signs.
- Cerebrospinal fluid (CSF) analysis revealed significant pleocytosis (546/mm3) with a predominance of polymorphonuclear cells (>70%), and CSF culture confirmed the presence of L. monocytogenes.
Findings:
- The patient was diagnosed with rhombencephalitis and treated initially with Penicillin G and Chloramphenicol.
- Subsequent therapy, guided by antibiogram, included a 4-week course of ampicillin followed by 10 days of imipenem.
- Follow-up CSF analysis indicated persistent pleocytosis and elevated protein levels, but the patient was discharged recovered.
Implications:
- This case underscores the potential for Listeria monocytogenes to cause severe CNS infections even in immunocompetent individuals.
- Effective antibiotic therapy, including ampicillin and imipenem, is crucial for managing listerial meningoencephalitis.
- Early diagnosis and aggressive treatment are vital for favorable outcomes in CNS Listeria infections.
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