Which statement about Listeria monocytogenes is not correct?

• A. Motile
• B. CAMP test positive
• C. Esculin hydrolysis positive
• D. Catalase negative

Answer: (D)

The test is about a key lab trait used to identify Listeria monocytogenes: the catalase enzyme. Listeria produces catalase, so it gives a positive catalase reaction (bubbling when hydrogen peroxide is added). A statement saying it is catalase negative conflicts with this well-established trait, making it the incorrect option.

Other reliable traits you’d expect with Listeria include motility at room temperature (tumbling movement) and a positive CAMP test with Staphylococcus aureus, which help distinguish it from other Gram-positive rods. Esculin hydrolysis is not a defining, consistently positive feature for Listeria, so relying on that test alone isn’t as informative for identification.