Listeria monocytogenes is a Gram-positive bacillus widespread in nature and responsible for human and animal infections. Listeriosis is a severe and rare infection transmitted orally and vertically, frequently in the context of an underlying immunosuppression. L. monocytogenes is able to cross several barriers: intestinal mucosa, placenta and blood-brain barrier. Listeriosis is associated with a range of clinical presentations: ranging from acute gastroenteritis, septicaemia, central nervous system and maternofetal infections. Diagnosis is based on the isolation of L. monocytogenes from blood and cerebrospinal fluid cultures. Treatment relies on the synergic combination amoxicillin and gentamicin, with a mortality rate up to 30% despite adequate therapy.