a genus of gram-negative aerobic bacteria that occus as pathogens and parasite in many animals (including humans)

Francisella is a genus of pathogenic, Gram-negative bacteria. They are small coccobacillary or rod-shaped, non-motile organisms, which are also facultative intracellular parasites of macrophages. Strict aerobes, Francisella colonies bear a morphological resemblance to those of the genus Brucella.