Case Report: Listeria monocytogenes Meningitis in an Immunocompetent Adult Patient

Objective: To report an interesting case of meningitis caused by Listeria monocytogenes in an immunocompetent adult. Patient and Methods: A previously healthy 25-year-old man presented with typical clinical features of meningitis. Cerebrospinal fluid (CSF) was obtained on the day of admission for biochemical and microbiological investigations. In addition, blood was also taken for culture and hematological studies. Antibiotic susceptibility test was performed using the Etest method. Microscopic examination of the CSF showed pleocytosis, which was predominantly lymphocytic, while the biochemical investigation revealed raised concentrations of protein and lactic acid as well as decreased glucose concentration. A 24-hour culture yielded pure growth of gram-positive bacilli identified by standard methods as L. monocytogenes. It was susceptible to ampicillin and trimethoprim-sulfamethoxazole. The patient was treated with intravenous ampicillin combined with gentamicin and made a complete recovery. Conclusion: This presentation describes an unusual case of meningitis caused by L. monocytogenes in a previously healthy young adult with no risk factor. Only a few similar cases have been reported in the literature.