Sepsis Due to Capnocytophaga canimorsus Following a Fox Bite: A Case Report

Capnocytophaga canimorsus is a commensal bacterium found in the oral flora of dogs and cats. Close animal contact with humans through biting, scratching, or wound licking may lead to transmission of this microorganism. Although infections are uncommon, they can be severe, particularly in individuals with predisposing risk factors. Transmission has most commonly been associated with dogs and, less frequently, cats. Reports involving other animal sources remain rare. We report the case of a male patient who presented to the Emergency Department with fever and abdominal pain approximately one week after sustaining a skin laceration on his right hand from a bite by a domesticated fox. He was promptly started on broad-spectrum antibiotics and responded quickly to treatment. Ten days after discharge from the hospital, blood cultures were reported positive for C. canimorsus. Severe infections with this bacterium have been reported in immunocompromised individuals but may also occur in previously healthy persons. Mortality rates from C. canimorsus sepsis range between 10% and 30%; therefore, prompt recognition and treatment are essential for favorable outcomes. Although a definitive causal relationship cannot be established without microbiologic testing of the animal source, the wound the patient presented with, and the recent exposure to a fox, raised concern for this. The temporal association between the fox bite and the patient’s illness raises the possibility of zoonotic transmission. This case highlights the importance of obtaining a detailed exposure history in patients presenting with sepsis of unclear origin and suggests that additional animal reservoirs for C. canimorsus may exist.