Capnocytophaga canimorsus (DF-2) Infection: A Continuing Challenge for Clinicians and Microbiologists

Capnocytophaga canimorsus, an opportunistic pathogen associated with dog bite or cat scratch, is a slow-growing, Gram-negative bacterium which causes serious complications in patients who are asplenic, alcoholic, or both. We report a case of meningitis and septicemia caused by C. canimorsus in a 66-year-old man who had a history of splenectomy and alcohol abuse as well as a recent dog bite. At the regional laboratory of a large health maintenance organization, C. canimorsus was isolated from cerebrospinal fluid and blood. To treat the multiple complications which developed, we administered cefotaxime, penicillin G, intravenous fluid, and methylprednisolone. The patient improved rapidly while receiving antimicrobial treatment. His uneventful recovery included reversal of hypotension, adult respiratory distress syndrome, and disseminated intravascular coagulopathy. In asplenic and immunocompromised patients, isolation and identification of C. canimorsus should be followed by appropriate antimicrobial treatment. Education about the dysgonic and capnophilic nature of this organism as well as its sources can prevent this animal-associated infection.