Listeria Rhombencephalitis: A Case of an Immunocompetent Adult

Listeriosis is one of the most important foodborne diseases, caused by a Gram-positive facultative anaerobic intracellular bacterium found in food and the environment, Listeria monocytogenes. It causes one of the most life-threatening bacterial infections of the central nervous system (CNS). Meningoencephalitis and rhomboencephalitis are the most common forms and immunosuppression represents the main risk factor. In this article, we report a case of severe, invasive Listeria monocytogenes rhombencephalitis in a healthy middle-aged man, admitted to our hospital with meningeal syndrome associated with left VI nerve palsy. No apparent abnormality was found in a head CT and brain magnetic resonance imaging. Following the preliminary LP results, a diagnosis of bacterial meningitis was suspected and empirical antibiotic and antiviral therapy was initiated. Because of the lack of any significant improvement in his clinical status, on day 2 of his admission, a genetic identification of CSF pathogens by high-throughput genome sequencing was performed and identified L. monocytogenes. The Clinical status improved with complete recovery after appropriate antibiotic treatment with sulfamethoxazole-trimethoprim. In conclusion, in an infectious context, pontine involvement should systematically evoke the diagnosis of listeriosis.