- Formerly known as Bacteroides
- Characteristics:
- Large Gram negative rods with terminal swellings
- Long polar fimbriae
- 16 antigenic types of fimbriae - used to differentiate strains antigenically
- All strains possess same O antigen
- Colonies of virulent strains have a dark central zone, a pale granular middle zone and an irregular periphery
- Strains detected by ELISA and PCR
- Thermostable proteases and elastase contribute to pathogenesis
- Keratinolytic proteases required for virulence
- Fimbriae required for adhesion to hoof
- Primary pathogen of epidermal tissues of hoof of ruminants, suriving briefly in the envionment
- Passed from animal to animal
- Causes foot rot in sheep along with other bacteria
- Ovine footrot:
- Contagious, economically important disease
- Wet pasture and hydrated stratum corneum leads to colonisation by Gram positive cocci and Arcanobacter pyogenes, followed by F. necrophorum; addition of D. nodosus causes footrot
- Can lead to loss of hoof
- Immunity:
- Homologous antibody to fimbrial antigen prevents adhesion and protects against footrot
- Antibody must penetrate the epidermal layers and reach adequate concentration on the skin surface
- Vaccine available