Members of the genus Capnocytophaga are filamentous Gram-negative bacilli. They are slow-growing aerobic and anaerobic bacteria and require presence of CO2 for their growth. The genus is classified into two groups: (a) dysgonic fermenter 1 (DF-1) and (b) dysgonic fermenter 2 (DF-2):
· DF-1 group consists of three species:Capnocytophaga ochracea,
Capnocytophaga gingivalis, and Capnocytophaga sputigena, whichare found as members of the normal flora of oropharynx in humans. These species have been associated with periodon-titis and bacteremia. They occasionally cause severe systemic disease, such as endocarditis in immunocompromised host.
· DF-2 group bacteria are found only in dogs and not inhumans.
Most Capnocytophaga strains are resistant to aminoglycosides but are sensitive to broad-spectrum cephalosporins, fluoroqui-nolones, and penicillins.