Bile Esculin Agar is prepared according to the formula specified by Swan, and later evaluated by Facklam and Moody. It was concluded that the bile esculin test provided a reliable means of identifying enterococci and differentiation from non-enterococci. Enterococci are bile tolerant and hydrolyze esculin which imparts a dark brown color to the medium. Gram positive bacteria other than enterococci are inhibited by the bile salts. A dehydrated culture medium recommended for the cultivation and presumptive identification of enterococci. (Alpha Biosciences # B02-107-500gm)
Use: A dehydrated culture medium recommended for the cultivation and presumptive identification of enterococci.
Description: Bile Esculin Agar is prepared according to the formula specified by Swan, and later evaluated by Facklam and Moody. It was concluded that the bile esculin test provided a reliable means of identifying enterococci and differentiation from non-enterococci. Bile Esculin Azide Agar is a more selective medium as described by lsenberg. Enterococci are bile tolerant and hydrolyze esculin which imparts a dark brown color to the medium. Sodium azide inhibits Gram negative and Gram positive bacteria other than enterococci are inhibited by the bile salts.
Formula* per Liter:
- Casein Digest of Peptone .............. 16.0g
- Esculin ................................. 1.0g
- Sodium Chloride ................................ 5.0g
- Oxbile ..................................10.0g
- Yeast Enriched Meat Peptone .......... 9.5g
- Sodium Citrate .....................1.0g
- Ferric Ammonium Citrate .................. 0.5g
- Sodium Azide .................... 0.25g
- Agar ...................................................14.0g
Final pH: 7.1 ± 0.2 at 25.0°C
* Grams per liter may be adj. or formula supplemented to obtain desired performance
Preparation: Mix 57 grams of the medium in one Liter of purified water until evenly dispersed. Heat with repeated stirring to dissolve completely. Distribute and autoclave at 121.0°C for 15 minutes.
Quality Control Specifications:
- The powder is homogeneous, free flowing and beige.
- Visually the prepared medium is a dark amber with bluish cast, and opalescent.
- Expected cultural response after 18-24 hours at 35°C.
Organism                                                                        Result
Escherichia coli ATCC 25922Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Inhibited, Esculin (-)
Enterococcus faecalis ATCC 29212Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Growth, Esculin (+)
Storage: Store the sealed bottle containing the dehydrated medium at 2 to 30.0°C. Once opened and recapped, place the container in a low humidity environment at the same storage temperature. Protect it from moisture and light. The dehydrated medium should be discarded if it is not free flowing or if the color has changed from the original beige color.
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