Hippurate Broth (3mL)

Determine the ability of an organism to hydrolyze sodium hippurate by enzymatic action using Thermo Scientific™ Remel™ Hippurate Broth. Heart muscle infusion and animal tissue peptone supply the variety of nutrients required for the growth of the majority of bacterial species. Sodium chloride maintains osmotic equilibrium. In 1922, Ayers and Rupp used an enriched medium containing hippuric acid to investigate the ability of bovine and human β-hemolytic streptococci to split hippuric acid into benzoic acid and glycine¹. In 1951, Leuthardt described hippuricase, the enzyme responsible for the hydrolysis of hippurate².

Braunstein et al. found the hippurate hydrolysis test to be useful for identification of group B streptococci (Lancefield group B)³. Facklam et al. recommended using the hippurate hydrolysis test in conjunction with bile esculin and 6.5% sodium chloride for identification of β-hemolytic streptococci belonging to groups A, B, and D⁴.

• Ready to use – Convenience of prepared media.
• Easy to interpret -
  • Positive test - A brown, flocculent, insoluble precipitate that persists on shaking
  • Negative test - No precipitate or formation of a precipitate that dissolves on shaking

This medium contains peptones and heart infusion that supply nitrogenous compounds and amino acids necessary for the growth of streptococci. Sodium chloride provides essential electrolytes and maintains osmotic equilibrium. The production of streptococcal antigenic hemolysin is stimulated by dextrose which is an energy resource. The buffers disodium phosphate and sodium carbonate counteract effects of acid produced during the fermentation of dextrose and prevent inactivation of the hemolysin. In the medium sodium hippurate is hydrolyzed by hippuricase to form benzoic acid and glycine. After the addition of ferric chloride (Hippurate Hydrolysis Reagent), ferric ions combine with benzoic acid to form ferric benzoate which is an insoluble precipitate.