Which organism hydrolyzes sodium hippurate to benzoic acid and glycine?

• A. Streptococcus agalactiae
• B. Streptococcus pneumoniae
• C. Listeria monocytogenes
• D. Enterococcus faecalis

Answer: (A)

The test hinges on detecting hippurate hydrolysis by hippuricase, which splits sodium hippurate into benzoic acid and glycine. When glycine is produced, a detection reagent (like ninhydrin) gives a color change, signaling a positive result. Streptococcus agalactiae is known to be hippurate hydrolysis positive, so it yields the color change indicating hippurate breakdown. This makes it a key differentiator for group B Streptococcus among the organisms shown, because the others typically do not hydrolyze hippurate in this assay. In clinical practice, a positive hippurate test helps identify group B strep, which is important in neonatal infection workups and maternal screening.