Taxonomy of the genus Listeria.

According to DNA homology values as well as to 16S rRNA cataloguing results, the genus Listeria presently contains two groups of closely related species: one is constitued by Listeria gravi and Listeria murrayi, the other by Listeria monocytogenes, Listeria ivanovii, Listeria innocua, Listeria welshimeri, and Listeria seeligeri. Among these seven species, only two are pathogenic for humans and animals: Listeria monocytogenes and Listeria ivanovii. Listeria denitrificans was recently excluded from this genus and transferred to a new genus, Jonesia, as Jonesia denitrificans.