A veterinarian presented with a fever of unknown cause. Blood cultures grown on specialized media revealed gram-negative short rods that tested positive for oxidase. Which organism is most likely responsible for the infection?

Explanation

The blood culture showed gram-negative short bacilli that are oxidase positive, which is characteristic of Brucella species. Pasteurella, Francisella, and Bartonella have different biochemical profiles, and Brucella is a common cause of pyrexia of unknown origin in veterinary professionals.