Capnocytophaga spp (canine)

• C. canimorsus
• C. cynodegmi

Gram Stain

• Gram negative bacilli fusiform with tapered ends in medium to long chains (facultative anaerobic)

Clinical Significance

These organisms are part of the commensal oral flora of dogs (occasionally cats and rabbits).

They can cause wound infections and septicemia in association with dog bites or close contact with dogs. 

Bacteremia can present as a mild illness in healthy individuals to a severe fulminant septicemia resembling meningococcemia in debilitated patients (asplenic, alcoholism, corticosteroid therapy).

Infections are often life-threatening in immunocompromised individuals especially if splenectomized.

Other associated infections include meningitis, endocarditis, pneumonia, cellulitis, septic arthritis, and ocular infections.

Usual Susceptibility Pattern

These organisms are usually susceptible to penicillins (some beta-lactamase producing strains are resistant).

They are susceptible to beta-lactamase inhibitor drugs, tetracyclines, 3rd generation cephalosporins, and carbapenems.

They are resistant to aminoglycosides and have variable susceptibility to TMP/SMX and quinolones.

Resistance to clindamycin and macrolides is common.