Which organism is a yellow pigment-producing, oxidase positive, nonmotile organism that does not grow on MacConkey agar?

The correct answer is based on the characteristics of the organism described in the question. Chryseobacterium meningosepticum is known for producing a yellow pigment and is oxidase positive, distinguishing it from many other nonmotile bacteria. Additionally, it is important to note that this organism does not grow on MacConkey agar, which is selective for Gram-negative bacteria that can ferment lactose, leading to a color change. Chryseobacterium meningosepticum does not ferment lactose, hence its inability to grow on this medium.

In contrast, Acinetobacter baumannii and Acinetobacter lwoffi belong to the genus Acinetobacter, which is typically oxidase negative and can grow on MacConkey agar, often appearing as colorless or light pink colonies due to lactose non-fermentation. Burkholderia cepacia, while an oxidase positive organism, is typically motile and also capable of growth on MacConkey agar, outcompeting lactose-fermenting species.

Thus, Chryseobacterium meningosepticum is the only organism among the options listed that fits all the specified criteria: it produces yellow pigment, is oxidase positive, nonmotile, and does not grow on MacConkey agar