A veterinary doctor had pyrexia of unknown origin. His blood culture in special laboratory media was positive for gram-negative short bacilli which was oxidase positive. Which one of the following is the likely organism grown in culture ?: (A) Pasteurella spp, (B) Francisella spp, (C) Bartonella spp, (D) Brucella spp
Answer is D. Points in favor of Brucellosis:

Veterinary doctor: Occupational exposure to infected animals
Organism could grow only in special laboratory media
Oxidase positive Gram-negative short bacilli
Brucellosis is one of the common cause of PUO