The value of bile tolerance together with hydrolysis of aesculin as a means of presumptively identifying enterococci / Group D streptococci is widely recognised^1,2,3,4,5.

The use of these parameters forms the basis of Bile Aesculin Agar and was described by Swan⁶ who concluded that the use of this medium is a valid alternative to Lancefield grouping for the recognition of enterococci / Group D streptococci.

Facklam⁷ further confirmed its usefulness in differentiating enterococci / Group D streptococci from non Group D streptococci while other workers have used the medium for presumptive identification of the Klebsiella-Enterobacter- Serratiagroup amongst the Enterobacteriaceae^8,9,10.

Technique
Using a sterile loop inoculate the medium with 4-5 colonies and incubate at 37°C for 18-24 hours.
The result is positive for bile salt tolerance and aesculin hydrolysis if blackening of the medium occurs.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.

Appearance
Dehydrated medium: Straw coloured, free-flowing powder
Prepared medium: Straw-brown coloured gel