Fusobacterium necrophorum is a causative organism, but there is disagreement about whether it can produce disease alone or invades synergistically with another organism, Bacteriodes melaninogenicus. Both organisms are nonmotile, anaerobic, gram negative bacteria that are routinely cultured from foot rot lesions.1 However, F. necrophorum is capable of causing foot rot by itself when experimentally injected into the skin of the interdigital space. Bacteriodes nodosus, the agent causing ovine foot rot, also may be involved.2 These organisms are common in the environment, and F. necrophorum is present in the rumen and feces of normal cattle.
Researchers do not agree on how long F. necrophorum can survive in the environment. One source states that the organism can survive for a maximum of one month,3 another that it can survive in soil for up to 10 months.1 Wet conditions, soil pH, and constant replenishment from cattle feces are probably the dominant reasons for the high numbers of these organisms in the environment. The factors that contribute to the pathogenicity of F. necrophorum include a potent endotoxin, a polysaccharide capsule, an exotoxin (a leukocidin), and a hemolysin.4 The leucotoxin kills phagocytic cells and allows the infection to persist.
Source: Virginia Tech Ag Extension