Which of the following organisms is NOT recognized as oxidase positive?

Yersinia enterocolitica is correctly identified as not being oxidase positive. This organism is a member of the Enterobacteriaceae family, which is generally characterized by being oxidase negative. Oxidase positivity is a biochemical test used to determine the presence of cytochrome c oxidase in bacteria, and this characteristic is not present in Yersinia enterocolitica.

In contrast, the other organisms listed have been studied for their oxidase activities. For example, Aeromonas hydrophilia, Pseudomonas aeruginosa, and Vibrio parahaemolyticus are all known to test positive for the oxidase enzyme. These bacteria possess the necessary cytochrome components that enable them to react in the oxidase test, making them oxidase positive. Thus, the distinction of Yersinia enterocolitica as oxidase negative is consistent with its classification within the family of Enterobacteriaceae.