Clinical Practice and Cases in Emergency Medicine

Introduction: Capnocytophaga ochracea is found in the human oral microbiome and is a rare cause of antibiotic-resistant, opportunistic septicemia in immunocompromised hosts. The zoonotic transmission of C ochracea from canines to humans has not yet been reported in the literature. Cohabitation with people is associated with oral colonization in dogs and may be a reservoir for Capnocytophaga infections, which have a decreased susceptibility to first-line antibiotics commonly used to treat animal exposures.

Case Report: This is the case of a 70-year-old male with a remote history of lymphoma status post splenectomy, in remission, who presented with stigmata of Capnocytophaga septicemia after a dog bite, which included purpura fulminans on physical examination. Initial broad-spectrum coverage with cefepime failed to slow the progression into multiorgan failure. A Capnocytophaga strain with extended resistance was suspected. Antibiotics were transitioned to meropenem, and the patient eventually made a good recovery. Blood cultures isolated C ochracea.

Conclusion: Capnocytophaga infections should be suspected in patients with severe sepsis and purpura fulminans after a canine exposure. Canine pets may be a reservoir for Capnocytophaga species with increased antibiotic resistances, such as C ochracea, which trace their origins to the human oral microbiome. A thorough medical history is essential to identify risk factors such as asplenia and active immune compromise that are associated with infections from antibiotic-resistant strains and worse outcomes. For Capnocytophaga infections that fail initial therapies, cephalosporins should be avoided because of high resistance rates, and the use of carbapenems may be favored over combination beta-lactam/beta-lactamase inhibitors in select clinical scenarios.