  francisella is a genus of pathogenic, gram-negative bacteria. they are small coccobacillary or rod-shaped, nonmotile organisms, which are also facultative intracellular parasites of macrophages. strict aerobes, francisella colonies bear a morphological resemblance to those of the genus brucella. the genus was named in honor of american bacteriologist edward francis, who, in 1922, first recognized f. tularensis (then named bacterium tularensis) as the causative agent of tularemia. == pathogenesis == the type species, f. tularensis, causes the disease tularemia or rabbit fever. f. novicida and f. philomiragia (previously yersinia philomiragia) are associated with septicemia and invasive systemic infections. == taxonomy == the taxonomy of the genus is somewhat uncertain, especially in the case of f. novicida (may be a subspecies of f. tularensis). in general, identification of species is accomplished 
Proteobacteria