Acinetobacter baumannii has which characteristic?

Acinetobacter baumannii has which characteristic?

• A. Requires cysteine
• B. Is oxidase negative
• C. Ferments glucose
• D. Does not grow on MacConkey agar

Answer: (B)

Acinetobacter baumannii is oxidase negative, meaning it lacks the enzyme cytochrome c oxidase and gives a negative oxidase test. This negative result helps distinguish it from oxidase-positive organisms like Pseudomonas. It is a nonfermenter that can grow on MacConkey agar as pale, non-lactose-fermenting colonies, so the statement about not growing on MacConkey is incorrect. It does not ferment glucose, which fits its nonfermenter status, and cysteine isn’t a defining requirement. The oxidase-negative trait is the most characteristic feature distinguishing this organism.

Acinetobacter baumannii is oxidase negative, meaning it lacks the enzyme cytochrome c oxidase and gives a negative oxidase test. This negative result helps distinguish it from oxidase-positive organisms like Pseudomonas. It is a nonfermenter that can grow on MacConkey agar as pale, non-lactose-fermenting colonies, so the statement about not growing on MacConkey is incorrect. It does not ferment glucose, which fits its nonfermenter status, and cysteine isn’t a defining requirement. The oxidase-negative trait is the most characteristic feature distinguishing this organism.