Which organism hydrolyzes sodium hippurate to benzoic acid and glycine?

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.

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.