Which species is hippurate hydrolysis positive among the listed organisms?

• A. L. micdadei
• B. L. longbeachae
• C. L. gormanii
• D. L. pneumophila

Answer: (D)

Hippurate hydrolysis tests whether an organism can break down hippurate into glycine and benzoic acid. If the organism has hippuricase, the substrate is cleaved and a detectable product forms, giving a positive result (often seen as a color change with the detection reagent).

Among the Legionella species listed, L. pneumophila is known to be hippurate hydrolysis positive, so it will yield a positive reaction in this test. The other species listed do not hydrolyze hippurate under standard test conditions, so they produce negative results. This test helps distinguish L. pneumophila from other Legionella species in the lab, supporting identification of the organism associated with Legionnaires’ disease.