INTRODUCTION:Capnocytophaga canimorsus is known to cause serious infection in immunocompromised patients. Here we describe a fatal case of C. canimorsus infection causing sepsis, disseminated intravascular coagulation (DIC), and purpura fulminans in an immunocompetent patient.
CASE PRESENTATION:A 63 year old female presented to her local emergency room with a 2 day history of fever, fatigue, and right upper quandrant abdominal pain radiating to her back. Her physical exam was remarkable for mild hypotension and right upper quadrant tenderness. Ultrasound of her abdomen showed cholelithiasis and gallbladder wall thickening. Blood cultures were obtained, and empiric antibiotics (ceftriaxone, ampicillin, metronidazole) and IV fluids were administered. She radically developed a purpuric rash and became more hypotensive and hypoxic. Urgent transfer to University of Wisconsin was initiated. Evaluation upon arrival to UW revealed temperature was 36.9 degrees C. Blood pressure 46/30 arrival, pulse of 129. She had extensive purpuric lesions involving face, trunk, and extremities. Chest examination revealed diminished breath sounds at her bases. Cardiac findings revealed tachycardia but no murmur. Abdomen had mild distention and tenderness with normal bowel sounds. Initial laboratories revealed a white blood cell count of 9300, hemoglobin of 12.4, and platelet count of 11,000. INR 4.2, PTT 138.9, d-dimer 14.4, and fibrinogen 105, Creatinine 2.2, AST 394, ALT 262, alkaline phosphatase 91, and total bilirubin 0.9. Initial arterial blood gas on 100% inspired oxygen showed a pH of 7.03, pCO2 31, PO2 80, and bicarbonate of 7.8. UA was normal. Chest x-ray was unremarkable. Patient was admitted to the ICU with diagnosis of septic shock and purpura fulminans. Vasopressors and antibiotics (vancomycin, ciprofloxacin, and cefepime) were started. Abdominal ultrasound revealed thicken GB wall with stones. Therefore, percutaneous cholecystostomy tube was placed. Normal appearing bile was recorded with no organisms on gram stain. Because of refractory acidosis despite adequate perfusion and bicarbonate infusion, she was begun on continuous renal replacement therapy. Activated protein C infusion was also initiated. Cultures from the outside hospital began growing small gram negative rods. Further history from family revealed that the patient had been caring for an ill dog the previous week. No bite or scratches had occurred, but she had frequently cleaned copious secretions from the dog’s mouth. The patient’s need for vasopressors continued to increase, her lactic acidosis worsened, and multisystem organ failure developed. Patient passed away 36 hours after ICU admission. Autopsy revealed no source of infection. Later, the gram negative rod was identified as Capnocytophaga canimorsus.
DISCUSSIONS:Capnocytophaga canimorsus is a fastidious, slow growing, gram negative bacteria that ferments carbohydrates. Infection usually occurs after dog or cat bite but cases have been reported after casual contact. The bacteria is part of the normal oral flora of dogs and does not cause disease in these animals. Severe infection in humans typically occurs in immunocompromised, neutropenic, and asplenic patients. Infection usually begins 2-3 days after a dog bite. The most common presentation is sepsis or meningitis. Rare case of severe sepsis with DIC and purpura fulminans have been reported, although those case occurred after a documented dog bite. In vitro studies have shown susceptibility of C. canimorsus to beta-lactams, doxycycline, fluoroquinolones, and clindamycin. Mortality is as high as 30% for septicemia and 5% for meningitis. Infections in immunocompetent host have been reported.
CONCLUSION:Capnocytophaga canimorsus infection should be suspected in cases of septic shock and purpura fulminans in pet owners with no clear source of infection. Although empiric broad spectrum antibiotics should provide adequate coverage, mortality remains high. Overwhelming sepsis and purpura fulminans in the absence of an animal bite in an immunocompetent host makes this case unique when compared to others reported in the medical literature.
DISCLOSURE:Robert Kim, None.