Bile Esculin Azide Agar

Description

Use and description:

It is a modified version of Bile Esculin agar with reduced bile salts concentration and addition of sodium azide, which gives better selectivity and good recovery of group D streptococci. Enterococci has the ability to hydrolyse esculin, the result is a dark to black-coloured compound that diffuses into the medium (black halo around the colonies).

Composition per litre:

Bile salts…………………………….10.00 g

Agar……………………………………15.00 g

Peptone………………………..……20.00 g

Sodium Chloride…………………..5.00 g

Yeast extract……………………..…5.00 g

Ferric citrate…………………….….0.50 g

Esculin…………………………………1.00 g

Sodium Azide …………………..…0.15 g

Final pH of the ready to use medium: 7.1 ± 0.2

Medium preparation:

Add 56.65 grams of dehydrated culture medium to 1 litre of distilled water. Heat with repeated stirring to dissolve completely. Distribute and autoclave at 121°C for 15 minutes.

Quality specifications:

Dehydrated medium: homogeneous, beige fine powder.

Ready to use medium: dark amber-greenish and opalescent medium.

Microbiological response:

Storage:

Dehydrated medium should be stored between 10 to 25°C. Once opened, place the container in a dark, dry place. The dehydrated medium should not be used if there is any lump or the colour has changed from the original.