Capnocytophaga canimorsus peritonitis in a simultaneous liver-kidney transplant recipient: A case report and review of the literature.

Capnocytophaga canimorsus is a fastidious, capnophilic Gram-negative rod transmitted through exposure to the oral secretions of domesticated dogs and cats and may cause severe infection in immunocompromised hosts. Bacterial peritonitis due to C. canimorsus is rare and has been reported primarily in patients receiving peritoneal dialysis. We describe a 66-year-old man status post simultaneous liver and kidney transplantation who presented with septic shock, neutropenia, acute kidney injury, and worsening ascites. Peritoneal fluid analysis demonstrated neutrophilic ascites consistent with bacterial peritonitis, although cultures were negative. Blood cultures and broad-range bacterial polymerase chain reaction using 16S rRNA gene sequencing identified C. canimorsus, confirming the diagnosis. The patient reported close contact with pet dogs and improved with targeted beta-lactam therapy. This represents the first reported case of C. canimorsus peritonitis in a solid organ transplant recipient and highlights the diagnostic value of molecular testing in culture-negative peritonitis.