Focusing on the main morphological and physiological characteristics of the food-borne pathogen Listeria monocytogenes

The genus Listeria spp includes fifteen species, i.e.L. monocytogenes, L. ivanovii, L. innocua,L. welshimeri, L. seeligeri, L. grayi, L. marthii, L. rocourtiae, L. fleichmannii, L. weihenstephanensis, L. floridensis, L. aquatic, L. cornellensis, L. ripariaand L. grandensis. Members of the genus Listeria are small Gram-positive rods sometimes arranged in short chains, ranging between 0.5 and 4 μm in diameter and between 0.5 and 2 μm in length. They are non-sporeforming and facultative anaerobic. Peritrichous flagella give them a typical tumbling motility, occurring at room temperature (20-25°C), but not at 37°C. Out of the fifteen species, L. monocytogenesis the major pathogen for humans. Very rare cases of infections due to L. ivanoviiand L. seeligeri have been described.