Enterococci · Confirmation and isolation
Bile Esculin Azide Agar – confirmation of intestinal enterococci
Bile Esculin Azide Agar (Enterococcus Agar) is used to confirm intestinal enterococci in water according to ISO 7899-2, after the membrane is transferred from Slanetz and Bartley Agar, and for the isolation of enterococci from food.
- Confirmation step of ISO 7899-2
- Black zone from esculin hydrolysis
- For water and food
How Bile Esculin Azide Agar works
Enterococci tolerate bile and hydrolyse esculin. The released esculetin reacts with ferric citrate and forms a brown to black zone around the colonies. Sodium azide and bile inhibit Gram-negative bacteria and most other Gram-positive bacteria.
Typical colony appearance
| Organism | Colonies |
| Enterococcus faecalis | Brownish-yellow colonies with a black zone |
| Escherichia coli, Staphylococcus aureus | Inhibited |
Technical data
| Preparation | 56.3 g/L; boil to dissolve, autoclave 121 °C 15 min |
| Final pH | 7.1 ± 0.2 |
| Incubation | 36 ± 1 °C, 24 h (isolation) |
| Storage | Dry, dark place; keep the container tightly closed |
Applications and practical notes
Enterococci and streptococci are tested in drinking, bathing and waste water, in food and in clinical and dairy laboratories, for example according to ISO 7899-2. Typical applications include:
- Drinking, bathing and recreational water
- Waste water and environmental samples
- Food and dairy products
- Clinical and veterinary microbiology
Working with Bile Esculin Azide Agar: Pre-warm the plates before transferring the membrane and read the black colouration of the medium after the incubation required by the method.
Good practice with dehydrated media: keep the bottle tightly closed in a cool, dry place, weigh the powder quickly to avoid moisture uptake, and use fresh distilled or deionised water. Check the pH of each new batch after preparation and before use, and label prepared media with the date. Performance of each lot can be verified with reference strains according to ISO 11133, the standard for the preparation, production, storage and performance testing of culture media.
About the Enterococcus methods: intestinal enterococci are indicators of faecal contamination of water. ISO 7899-2 counts them by membrane filtration on Slanetz and Bartley Agar, where typical colonies are red, maroon or pink, and confirms them by transferring the membrane to Bile Esculin Azide Agar, where esculin hydrolysis turns the medium black. In food, enterococci are counted on bile esculin azide media. Streptococci are cultivated on blood agar, where the type of haemolysis is read, and grouped by Lancefield antigens. COLO.Science offers media, supplements, rapid tests and identification kits for these methods.
Complete sets from one supplier: COLO.Science supplies culture media, supplements, rapid tests, identification kits and QC strains as complete sets for the method you follow. Send us your sample types and standards, and we will prepare an offer with the matching products and documentation.
Bile Esculin Azide Agar is supplied by COLO.Science in the pack sizes listed under Ordering information. For larger quantities, regular deliveries or method-specific sets that include Bile Esculin Azide Agar, please send us a request. With every delivery of Bile Esculin Azide Agar you receive the lot number and expiry date, and on request we send the available documentation for Bile Esculin Azide Agar.
Where Bile Esculin Azide Agar fits in Enterococcus and Streptococcus testing
- Enumeration in water – membrane filtration on Slanetz and Bartley Agar
- Confirmation – transfer of the membrane to Bile Esculin Azide Agar; Bile Esculin Agar for single colonies
- Streptococci – Blood Agar Base with blood for haemolysis, Mitis Salivarius Agar with potassium tellurite
- Identification – Lancefield grouping latex, qPCR or LAMP for Enterococcus faecalis
See all Enterococcus and Streptococcus products in the Microbiology Catalogue →
Ordering information
| Product | COLO code | Pack |
|---|---|---|
| Bile Esculin Azide Agar (Enterococcus Agar) | PRO7496 | 500 g |
Product notice: preparation, storage conditions and shelf life are given on the label. Technical data on this page are for orientation; the label and the lot documentation apply. B2B prices are quoted net, excluding VAT.
Sales and technical support
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Quotations and technical support for culture media and microbiology products across our international sales territory. B2B prices are net, excluding VAT.
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Need the complete set for your method?
Send the sample type, target organism and the standard you follow. COLO.Science will put together the media, supplements, QC strains and confirmation tests for the whole procedure.
