Newly named in 1989, Capnocytophaga canimorsus is a bacterial pathogen found in the saliva of healthy dogs and cats, and is transmitted to humans principally by dog
bites. This review compiled all laboratory-confirmed cases, animal sources, and virulence attributes to describe its epidemiology, clinical features, and pathogenesis. An estimated 484 patients with a median age of 55 years were reported, two-thirds of which were male. The case-fatality rate was about 26%. Its clinical presentations included
severe sepsis and fatal
septic shock,
gangrene of the digits or extremities, high-grade
bacteremia,
meningitis,
endocarditis, and
eye infections. Predispositions were prior
splenectomy in 59 patients and
alcoholism in 58 patients. Dog
bites before illness occurred in 60%; additionally, in 27%, there were scratches, licking, or other contact with dogs or cats. Patients with
meningitis showed more advanced ages, higher male preponderance, lower mortality, and longer incubation periods after dog
bites than patients with
sepsis (p < 0.05). Patients with prior
splenectomy presented more frequently with high-grade
bacteremia than patients with intact spleens (p < 0.05). The organism possesses virulence attributes of
catalase and
sialidase production, gliding motility,
cytotoxin production, and resistance to killing by serum
complement due to its unique
lipopolysaccharide.
Penicillin is the
drug of choice, but some practitioners prefer
third-generation cephalosporins or
beta-lactamase inhibitor combinations. C. canimorsus has emerged as a leading cause of
sepsis, particularly post-
splenectomy sepsis, and
meningitis after dog
bites.