Fusobacterium

Fusobacterium is a genus of anaerobic, Gram-negative bacteria, which are part of the normal flora of the human oropharynx, gastrointestinal tract, and female genital tract. The bacteria from this genus are known for their elongated, spindle shape, and they are involved in several human diseases, including periodontal diseases, Lemierre's syndrome, and potentially colorectal cancer. Fusobacterium species have also been implicated in other infections such as peritonsillar abscesses and pleuropulmonary infections.

Characteristics

Fusobacterium species are non-spore-forming, obligate anaerobes that can vary in shape from long filaments to more coccobacillary forms. They do not possess flagella but some species are capable of gliding motility. Fusobacterium nucleatum, in particular, is known for its ability to adhere to and invade human epithelial and endothelial cells, a trait that facilitates its role in oral and systemic infections.

Pathogenesis

The pathogenicity of Fusobacterium is linked to its ability to adhere to host cells and to co-aggregate with other bacteria. This co-aggregation is crucial for the development of dental plaque and periodontal disease. Fusobacterium species produce a variety of virulence factors, including but not limited to, FadA adhesin which facilitates adherence and invasion of host cells, and lipopolysaccharides (LPS) which can induce inflammation.

Periodontal Disease

Fusobacterium is a key player in the development of periodontal disease, contributing to the complex biofilm that forms on the teeth and gums. Its interaction with other oral bacteria can exacerbate the inflammatory response and lead to tissue destruction.

Lemierre's Syndrome

Lemierre's syndrome, often caused by Fusobacterium necrophorum, is a rare but life-threatening condition characterized by thrombophlebitis of the internal jugular vein and metastatic infections, following an oropharyngeal infection.

Colorectal Cancer

Recent studies have suggested a possible link between Fusobacterium and colorectal cancer. The bacteria's presence in tumors has been associated with worse clinical outcomes, although the exact mechanism of how Fusobacterium contributes to cancer progression is still under investigation.

Diagnosis and Treatment

Diagnosis of Fusobacterium infections involves culturing the bacteria from clinical specimens, which can be challenging due to their strict anaerobic growth requirements. Molecular methods, such as PCR, are increasingly used for rapid identification.

Treatment typically involves the use of antibiotics. Penicillin, metronidazole, and clindamycin are among the antibiotics that are effective against Fusobacterium infections. In cases of Lemierre's syndrome, prolonged antibiotic therapy and, in some cases, surgical intervention to remove infected thrombi may be necessary.

Prevention

Good oral hygiene and regular dental check-ups are essential in preventing infections caused by Fusobacterium, especially periodontal disease. Awareness and early treatment of oropharyngeal infections can reduce the risk of developing more severe conditions like Lemierre's syndrome.