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:
| Organism | Result |
| Escherichia coli ATCC 25922 | Partially inhibited, no colour |
| Enterococcus faecalis ATCC 29212 | Growth, Esculin (+) |
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.