Fusobacterium species are long, anaerobic, gram-negative rods with pointed ends (Figure 1). They are part of the human normal flora of the mouth, colon, and female genital tract and are isolated from brain, pulmonary, intra-abdominal, and pelvic abscesses. They are frequently found in mixed infections with other anaerobes and facultative anaerobes.
Fig1. Fusobacterium nucleatum—Gram stain. Note the long, thin gram-negative rods with pointed ends. (Used with permission from Dr. Dowell VR, Jr. Public Health Image Library, Centers for Disease Control and Prevention.)
Fusobacterium nucleatum occurs, along with various spirochetes, in cases of Vincent’s angina (trench mouth), which is characterized by a necrotizing ulcerative gingivitis. Fusobacterium necrophorum causes Lemierre’s disease, which is an anaerobic infection of the posterior pharyngeal space accompanied by thrombophlebitis of the internal jugular vein and metastatic infectious emboli to the lung.
The laboratory diagnosis is made by culturing the organism anaerobically. The drug of choice for Fusobacterium infections can be penicillin G, clindamycin, or metronidazole. There is no vaccine.
