Capnocytophyga is best characterized as

While admittedly rare in human medicine, the bacteria referred to should be appreciated for their role in human disease. Branhamella is a Gram-negative diplococcus. It has recently been renamed Moraxella catarrhalis. While it is a member of the normal flora, it may cause severe upper and lower respiratory tract infection, particularly in the immunosuppressed patient. Most isolates produce b-lactamase and are resistant to penicillin. Cardiobacterium, as the name implies, causes endocarditis. This small Gram-negative pleomorphic rod may take a few days to grow. Infection is usually endogenous in that Cardiobacterium is part of the normal flora of the gut. Capnocytophaga grows best in a carbon dioxide atmosphere as the name implies. It is isolated frequently from patients with periodontal disease but may also cause septicemia in susceptible patients. Rat-bite fever is caused by Spirillum and the agent of cat scratch disease is B. henselae.