Case Presentation: A 48-year-old man with a past medical history of congenital solitary right kidney, chronic idiopathic pancreatitis, pancreatectomy and islet cell transplant, splenectomy, and alcohol use disorder presented with fever, chills, and night sweats. He was bitten by a dog three days prior to presentation. Shortly after arrival, he developed septic shock with lactic acidosis and acute kidney injury. On physical exam, the patient was noted to be cyanotic, diaphoretic, febrile, exhibited delayed capillary refill, and had a forehead wound consistent with a dog bite. He was emergently intubated, resuscitated with intravenous fluids and required vasopressors. Blood cultures were collected and empiric antibiotics were initiated with vancomycin and meropenem. A computed-tomography (CT) scan of the abdomen and pelvis showed changes consistent with hepatic steatosis but no signs of acute infection. CT of the head and face were both unremarkable. Seventy-two hours later, the blood cultures grew Capnocytophaga canimorsus. The antibiotic regimen was changed to piperacillin-tazobactam and he was given a one-time dose of intravenous immunoglobulin (IVIG). He had an extensive hospital course that was complicated by stress induced cardiomyopathy requiring ionotropic support, worsening coagulopathy in the setting of disseminated intravascular coagulation, acute renal failure requiring renal replacement therapy, and severe alcohol withdrawal. He was eventually discharged home.
Discussion: Dogs have long been referred to as “man’s best friend”, however this relationship is not without risk. Capnocytophaga canimorsum is an anaerobic, fastidious and slow growing gram-negative bacillus and oral commensal found primarily within the microbiome of dogs and some cats. [1-2] Although rare, infections due to this organism are typically the result of a dog bite or scratch and can lead to severe, rapidly progressive septicemia, endocarditis, gangrene and/or meningitis in certain patient populations. [3-6] Those at greatest risk for severe infections are patients with decreased inherent immunity due to anatomical or functional asplenia, advanced or end stage liver disease, alcohol use disorder, or immunosuppression. [3] Recognition of these risk factors is key in initiating proper empiric antibiotics, thus decreasing overall morbidity and mortality.
Conclusions: Characterization of the clinical presentation associated with C. canimorsum infection is important given its potential to cause rapid deterioration due to fulminant infection. Blood cultures can take up to fourteen days to grow, so a high index of suspicion is necessary in the appropriate clinical setting when deciding empiric antibiotic therapy in patients who present with dog-bite associated infections. Our case highlights a classic presentation of fulminant septic shock due to Capnocytophaga canimorsum following a dog bite, but is unique because our patient had multiple risk factors.