Capnocytophaga canimorsus Endocarditis Presenting with Leukocytoclastic Vasculitis and Glomerulonephritis

Capnocytophaga canimorsus is a gram-negative bacterium commonly found in the saliva of dogs and cats. Despite the frequency of animal bites, infection with Capnocytophaga species is rare, and severe infections are usually associated with underlying risk factors, such as alcohol use disorder, asplenia, or immunosuppression. We describe a case of a man who presented with a purpuric rash, lower extremity edema, and acute renal failure and was found to have tricuspid valve endocarditis and infection-associated glomerulonephritis due to C. canimorsus. Despite treatment with cefepime, the vegetation increased in size and valvular function worsened. He was readmitted with an inferior wall myocardial infarction, heart failure, and pulmonary embolism. He underwent an urgent tricuspid valve replacement with a bioprosthetic valve. A 16S ribosomal RNA amplicon sequencing performed on the resected valve tissue verified involvement of C. canimorsus. Post-operatively, he had several episodes of gastrointestinal hemorrhage requiring multiple endoscopic interventions and arterial embolization. The recurrent gastrointestinal hemorrhage combined with his severe functional decline ultimately led to his death. This patient had an uncommon presentation with leukocytoclastic vasculitis and infection-associated glomerulonephritis, which revealed an underlying diagnosis of infective endocarditis due to C. canimorsus, a rare gram-negative bacterial etiology of infective endocarditis.