Fusobacteria is a group of anaerobic, gram-negative bacteria with a chemoorganotrophic heterotrophic metabolism. These rod-shaped bacteria are found in cavities of humans and other animals. No endospores are formed. Some species are pathogenic and occur in various pus-forming infections including gingivitis, dental abscesses, mandibular space infections, periodontal infections, and stomatitis. Liver abscesses arise with the organisms that inhabit the rumen gaining entry into the portal circulation, and are often secondary to ruminal acidosis and rumenitis complex in grain-fed cattle.
Fusobacterium is found as part of the normal flora in human oropharynx, gastrointestinal tract and female genitalia. Fusobacterium necrophorum can, in rare cases, cause Lemierre's syndrome, a potentially life-threatening disease characterised by septic pulmonary embolism and vena cava thromboembolism.3. Leptotrichia is isolated from patients with gingivitis. Dental scaling is widely considered as the most effective anti-gingivitis treatment.4. Propionigenium comprises fermentative species. Streptobacillus naturally harbored in the oral cavity and upper respiratory tract rats; pathogenic to humans.Fusobacterium fusiforme
Fusobacterium necrophorum, a Gram-negative, non-spore-forming anaerobe, is a normal inhabitant of the alimentary tract of animals and humans. Two subspecies of F. necrophorum, subsp. necrophorum (biotype A) and subsp. funduliforme (biotype B), have been recognized, that differ morphologically, biochemically, and biologically. The subsp. necrophorum is more virulent and is isolated more frequently from infections than the subsp. funduliforme. The organism is an opportunistic pathogen that causes numerous necrotic conditions (necrobacillosis), either specific or non-specific infections, in a variety of animals. Of these, bovine liver abscesses and foot rot are of significant concern to the cattle industry.
The pathogenic mechanism of F. necrophorum is complex and not well defined. Several toxins or secreted products, such as leukotoxin, endotoxin, hemolysin, hemagglutinin, proteases, and adhesin have been implicated as disease causing (virulence) factors. The major virulence factor appears to be leukotoxin, a secreted protein of high molecular weight, active specifically against leukocytes of ruminants. The leukotoxin appears to be a new protein and does not share sequence similarity with any other leukotoxin. F. necrophorum is also a human pathogen and the human strains appear to be different from the strains involved in animal infections.
Streptobacillus moniliformis is the causative agent of streptobacillary rat-bite fever. It is also associated with amnionitis, bacteremia, brain abscess, cutaneous and subcutaneous abscesses, endocarditis, female genital tract abscess, palmoplantar pustulosis, septic arthritis, spinal epidural abscess, splenic abscess, spondylodiscitis with psoas abscess, and synovitis.5