Poster Presentation Australian Society for Microbiology Annual Scientific Meeting 2014

Endocarditis after Dog Bite (#365)

Lorieza Castillo 1 , Joel Douglas 1 , Letitia Gore 2 , Chistopher Cole 3 , David Looke 2 , Claire Heney 1
  1. Division of Microbiology, Pathology Queensland, Princess Alexandra Hospital, Woolloongabba, QLD, Australia
  2. Infectious Diseases, Princess Alexandra Hospital, Woolloongabba, QLD, Australia
  3. Division of Surgery, Princess Alexandra Hospital, Woolloongabba, QLD, Australia

Capnocytophaga canimorsus is a commensal, Gram-negative, fusiform bacillus living in the oral cavities of dogs and cats1 2. It has been implicated in severe human infections, mainly septicaemia, meningitis, septic arthritis, and more rarely, infective endocarditis with only 19 cases in the published literature since its identification in 19763-7 .

We are presenting a case of a 57-year-old man with bicuspid aortic valve endocarditis complicated by aortic root abscess caused by C. canimorsus secondary to a dog bite. The patient underwent cardiac surgery for aortic valve replacement and patch repair of the abscess.  The excised aortic valve tissue along with multiple blood cultures were submitted for culture. All specimens grew Capnocytophaga sp. which was identified phenotypically. The patient was post-operatively treated with intravenous ceftriaxone for six weeks. Three weeks after the completion of antibiotics, the patient presented with decompensated cardiac failure. Echocardiogram revealed an acute severe aortic regurgitation with new root abscess formation and dehiscence of the prosthetic valve. The patient underwent urgent surgery for replacement of the bioprosthetic aortic valve and patch repair of the abscess. All blood cultures collected thereafter, including the bioprosthetic aortic valve & root abscess were all culture-negative. 16s PCR amplification and sequencing on the subsequent aortic root abscess detected the presence of Capnocytophaga canimorsus. Initial attempts to secure the valve and repeated patch repair were successful but ongoing bleeding, and subsequent repeated attempts to repair the defect resulted in cardiopulmonary failure not consistent with survival and the patient was declared deceased ten hours into the operation.

This case highlights the capacity of Capnocytophaga canimorsus to produce bicuspid aortic valve endocarditis and root abscess. It also illustrates the possibility of a relapse of C. canimorsus endocarditis leading to a fatal outcome which has never been documented in the literature.

  1. Bobo RA, Newton EJ. A previously undescribed gram-negative bacillus causing septicemia and meningitis. Am J Clin Pathol 1976;65:564-9.
  2. Westwell AJ, Spencer MB, Kerr KG. DF-2 bacteremia following cat bites. Amer J Med 1987; 83: 1170.
  3. Lion, C., Escande, F. & Burdin, J. C. (1996) Capnocytophaga canimorsus infections in human: Review of the literature and cases report. Eur J Epidemiol, 12, 521-33.
  4. Sandoe, J. A. (2004) Capnocytophaga canimorsus endocarditis. J Med Microbiol, 53, 245-8.
  5. Coutance, G., Labombarda, F., Pellissier, A., Legallois, D., Hamon, M., Bachelet, C. & Lepage, O. (2009) Capnocytophaga canimorsus endocarditis with root abscess in a patient with a bicuspid aortic valve. Heart Int, 4, e5.
  6. Frigiola, A., Badia, T., Lovato, R., Cogo, A., Fugazzaro, M. P., Lovisetto, R. & Di Donato, M. (2003) Infective endocarditis due to Capnocytophaga canimorsus. Ital Heart J, 4, 725-7.
  7. Hayani, O., Higginson, L. A., Toye, B. & Burwash, I. G. (2009) Man's best friend? Infective endocarditis due to Capnocytophaga canimorsus. Can J Cardiol, 25, e130-2.