Diagnostic Challenges in Capnocytophaga canimorsus Sepsis: A Case Report

Capnocytophaga canimorsus infections, though rare, can be severe. Diagnosis is straightforward with a known dog-bite history, but is challenging otherwise. A 67-year-old woman with no immunodeficiency or alcohol abuse history presented with high fever (41.5°C), vomiting, and altered consciousness. No neck stiffness or peritoneal irritation was observed. Laboratory tests showed elevated liver enzymes, creatine kinase, inflammatory markers, and lactate. Computed tomography suggested strangulated ileus, which was ruled out during emergency laparotomy. Postoperatively, she experienced shock and was treated with vasopressors, corticosteroids, and ampicillin-sulbactam. Her condition improved, and blood culture showed Gram-negative rods. On day 3, her husband mentioned a recent dog bite, and a Capnocytophaga infection was suspected. Continued treatment with ampicillin-sulbactam improved her symptoms, and she was discharged. Blood cultures confirmed C. canimorsus on day 10. In severe sepsis with delayed bacterial identification, C. canimorsus should be considered. Repeated history-taking and empirical beta-lactamase inhibitor treatment are crucial.