Gram staining
Listeria ivanovii is a species of bacteria in the genus "Listeria". The listeria are rod-shaped bacteria and become positively stained when subjected to Gram staining. Of the six bacteria species within the genus, "L. ivanovii" is one of the two pathogenic species (the other being "L. monocytogenes"). It behaves like "L. monocytogenes", but is found almost exclusively in ruminants (mainly sheep). The species is named in honor of Bulgarian microbiologist Ivan Ivanov.