Which Legionella species is positive for hippurate hydrolysis?

Which Legionella species is positive for hippurate hydrolysis?

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

Answer: (D)

Hippurate hydrolysis checks whether the organism has hippuricase, an enzyme that cleaves hippurate into glycine and benzoic acid. L. pneumophila is known to possess this enzyme, so when hippurate is given in the test, it’s hydrolyzed and a detectable positive reaction appears (often seen as a purple color due to glycine detection). Among the Legionella species listed, L. pneumophila uniquely shows this positive result, while the others do not, making hippurate hydrolysis a useful differential test to identify L. pneumophila.

Hippurate hydrolysis checks whether the organism has hippuricase, an enzyme that cleaves hippurate into glycine and benzoic acid. L. pneumophila is known to possess this enzyme, so when hippurate is given in the test, it’s hydrolyzed and a detectable positive reaction appears (often seen as a purple color due to glycine detection). Among the Legionella species listed, L. pneumophila uniquely shows this positive result, while the others do not, making hippurate hydrolysis a useful differential test to identify L. pneumophila.