Question

What is one test that can be used to differentiate Enterococcus organisms (broadly, or Enteroccus raffinosus specifically) from other Gram positive organisms? On what basis does it differentiate between them?

Answer 1

Bile Esculin Agar Test
This test is helpful in differentiating the Enterococcus bacteria from the other gram positive bacteria because it contains media which is both selective and differential. It tests the ability of organisms to hydrolyse esculin in the presence of bile. Bile inhibits the growth of Gram-positive bacteria other than enterococci whereas sodium azide inhibits the growth of Gram-negative bacteria.
The positive result for this test is marked by the colour change from pale brown to black or dark brown this happens only when the organism can hydrolyse esculin in presence of bile.
If organisms is not capable of doing so, the dark brown colour or black colour is not produced.