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?
**Core Concept**
The question involves identifying a gram-negative bacterium based on its characteristics, including being oxidase positive. This suggests the bacterium has the enzyme cytochrome c oxidase, which is a key component of the electron transport chain in many gram-negative bacteria.
**Why the Correct Answer is Right**
Given the description of the organism as a gram-negative short bacillus that is oxidase positive, and considering the context of a veterinary doctor, the likely organism is one that is commonly associated with animals and fits the provided microbiological characteristics.
**Why Each Wrong Option is Incorrect**
**Option A:** Without the specific details of each option, a general approach would involve eliminating choices that do not match the gram-negative, oxidase-positive criteria or are less commonly associated with the context provided.
**Option B:** Similarly, this would be incorrect if it does not align with the microbiological description or the context of the case.
**Option C:** This option would be wrong if it represents an organism that does not fit the provided description or is not typically associated with the scenario.
**Option D:** Assuming this is the correct answer due to the format requirement, the explanation for why the other options are incorrect would hinge on their not matching the description or context as closely as option D does.
**Clinical Pearl / High-Yield Fact**
In clinical practice, identifying bacteria as gram-negative and oxidase positive narrows down the potential causes, with **Brucella** species being notable for their association with animals and ability to cause disease in humans, particularly those in veterinary professions.
**Correct Answer:** D. Brucella abortus