Listeria Monocytogenes Meningitis in an Immunocompetent Patient

Listeria monocytogenes (LM), one of the most important foodborne pathogens, is an intracellular bacterium found in food and the environment. It causes listeriosis, a potentially severe disease, particularly for pregnant women, the elderly and immunocompromised patients, but in rare cases, it can cause invasive disease in immunocompetent adults and children. Community-acquired bacterial meningitis caused by LM is rare and difficult to diagnose. It carries a high mortality rate; therefore, it is essential to start appropriate antibiotic treatment as soon as possible. The first case of LM meningitis identified in our hospital over the last 10 years is that of a previously healthy 45-year-old man who presented in the emergency department with a 4-day history of diplopia, left eye medial deviation and left palpebral ptosis, with no history of fever, headache or gastrointestinal symptoms. Because of the atypical symptoms, a suspicion of meningitis vs cerebral aneurysm was raised during the admission process. The patient was diagnosed with LM meningitis and recovered fully after appropriate antibiotic treatment. The purpose of this article is to emphasise the possibility of LM invasive disease (in this case meningitis) occurring in previously healthy individuals and to raise awareness about the need for LM to be considered in the differential diagnosis of atypical presentations.