Used to identify group A streptococci and enterococci
Principle: L-naphthylamide-β-naphthylamide in the test medium is hydrolyzed, releasing free β-naphthylamide. The reagent, N, N-dimethylaminocinnamaldehyde, is added. It joins with β-naphthylamid, if present, to form a red Schiff base.
Procedure:
Select 2 to 3 colonies with a loop and emulsify into PYR broth
Incubate at 35ºC for 4 hours
Add one drop of PYR reagent and observe for color change
Read and record the reaction at 1 minute
Interpretation
Deep red cherry within a minute of the addition of the reagent is positive
