Capnocytophaga canimorsus in Iliac Artery Mycotic Aneurysm: The Role of Molecular Diagnostics

BACKGROUND The bacterial organism Capnocytophaga canimorsus is an oral commensal of cats and dogs and can cause life-threatening infections like mycotic aneurysm, meningitis, and sepsis. Mycotic aneurysms occur when microbial infections cause arterial wall degeneration. Difficulty in diagnosing Capnocytophaga canimorsus infection can occur due to the bacteria's fastidious nature and laboratory testing limitations, contributing to the infection's high morbidity and mortality. This report describes the case of a patient with an iliac artery mycotic aneurysm 2 months after a dog bite. Identification of Capnocytophaga canimorsus was achieved through polymerase chain reaction. CASE REPORT The 67-year-old female patient presented initially with nonspecific abdominal pain. Imaging revealed a right iliac artery abnormality suspicious for mycotic aneurysm. Capnocytophaga canimorsus was identified through broad-range bacterial polymerase chain reaction after standard culture failed to determine the infectious etiology. A history of dog bite was discovered after diagnosis. When standard culture cannot provide a diagnosis, 16s rRNA polymerase chain reaction is the preferred molecular-based test at our institution. CONCLUSIONS Through presentation of a case of Capnocytophaga canimorsus mycotic aneurysm in an immunocompetent woman, this report illustrates the importance of familiarity with Capnocytophaga canimorsus and molecular laboratory methods in achieving favorable outcomes when faced with Capnocytophaga canimorsus infection. In these difficult cases, 16s rRNA polymerase chain reaction and similar molecular technologies are becoming essential. This case also highlights thorough history-taking as essential for guiding correct diagnosis and reinforces that infection with Capnocytophaga canimorsus should be investigated when there is a history of dog bite.