Bacteroides Bile Esculin (BBE) Agar

Bacteroides Bile Esculin Agar is an enriched, selective, and differential medium recommended for the isolation and presumptive identification of obligatory anaerobic gram-negative bacilli of the Bacteroides fragilis group and Bilophila spp. Livingston et al formulated this medium that contained kanamycin to achieve recognition of the Bacteroides fragilis group within 48 hours1, 2. Gentamicin was later substituted for kanamycin because it does not lose potency at incubation temperatures2. The 100ug/ml of gentamicin inhibits most aerobic organisms and 20% bile inhibits most other anaerobes. Esculin and iron have been incorporated into the agar as differential agents to aid in detecting the esculin-positive B. fragilis group organisms. This medium is a very useful medium for Bilophila species, which usually produce black-centered colonies on this medium due to H2S production. Other organisms that may grow on this medium are occasional strains of Fusobacterium mortiferum and F. varium, gentamicin-resistant Enterobacteriaceae, enterococci, pseudomonads, staphylococci, and yeast. However, the colony size of the facultative anaerobic organisms is usually less than 1mm in diameter.

Bacteroides Bile Esculin Agar is packaged in an oxygen-free, reduced state to prevent the formation of toxic oxidized by-products that may damage obligate anaerobes and inhibit the growth of more fastidious species. Therefore, ingredients have been added to the medium to neutralize the growth inhibiting effects of peroxide and other reactive oxygen species (ROS) that may develop during the medium's brief exposure to oxygen after it is sterilized and before it is packaged in an oxygen-free environment.

Product NameCatalog #Quantity
Bacteroides Bile Esculin Agar mono plate, 90 x 15 mm CB9130P 10/pk

Quality Control

The following organisms are routinely used for testing for this medium.
Test OrganismsResults
aBacteroides fragilis ATCC® 25285 Growth; (+)
aProteus mirabilis ATCC® 12453 Inhibited; (-)
aRecommended QC strains for User Quality Control according to the CLSI document M22 when applicable.

User Quality Control

Check for signs of contamination and deterioration. Users of commercially prepared media may be required to perform quality control testing with at least one known organism to demonstrate growth or a positive reaction; and at least one organism to demonstrate inhibition or a negative reaction (where applicable).

Ingredients g/L

(Final pH 7.0 +/- 0.3 at 25°C)Oxbile (Oxgall)20.0
Tryptic Soy Agar 45.0
Reducing Agents/Peroxide Inhibitors 1.5
Esculin 1.0
Ferric Ammonium Citrate 0.5
Hemin 12.0
Gentamicin 100.0
2 total citations

  1. Dowell, V.R., Jr. and T.M. Hawkins. 1987. Laboratory Methods in Anaerobic Bacteriology. In: CDC Laboratory Manual. DHEW Publication No. (CDC) 87-8272. U.S. Department of Health, Education and Welfare, Public Health Service, Center for Disease Control, Atlanta, GA
  2. Livingston, S.J. et al. 1978. J. Clin. Microbiol.; 7:448-453
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