Ready-to-use media
Bile Esculin Azide Agar ISO
Solid medium for the confirmation and enumeration of enterococci in clinical samples and water samples by the membrane filtration method according to ISO 7899-2.
- Cat. No.
- LC-4701
- Category
- Ready-to-use media
- Format
- 30 water plates, 55 mm
- ISO 17025 quality control
- Yes
- Storage
- 2 to 25 °C
- Minimum guaranteed shelf life
- 2 months
- Standards
- ISO 7899-2
- Also available
- Ready-to-use medium, 1 format (LC-952)
- Also available
- Dehydrated medium, 1 format (LC-1005)
- Also available
- Dehydrated medium, 1 format (LC-1372)
Bile Esculin Azide Medium is a modification of the classical Bile Esculin proposed by Isenberg, Goldberg and Sampson in 1970, but with a reduction in the amount of bile and the addition of sodium azide. Brodsky and Schiemann showed that this medium, also known as Enterococci Selective Medium, gave the best results using the membrane filtration technique.
Key features
Applications
Selective isolation of enterococci.
Industry
Water.
Standards
ISO 7899-2.
Presentation
30 prepared plates, 55 mm, for filtration purposes, with 9 ± 1 mL.
Description and technique
Description
The current formulation according to ISO Standard 7899-2:2000 is used for the second step in the confirmation and enumeration of enterococci in water by the membrane filtration method. The colonies previously selected on Slanetz Bartley Agar must be confirmed by a short incubation on Bile Esculin Azide Medium for verification of esculin hydrolysis in a selective environment.
Technique
After an incubation of 24-48 hours on Slanetz Bartley Agar, the membrane filter showing typical colonies is transferred, with sterile forceps in an upright position, to a pre-warmed plate of Bile Esculin Azide Agar. After two hours of incubation at 44 ± 0.5 °C the membrane filter is inspected. All the typical colonies that show brown to black colour in the surrounding medium are considered positive and therefore intestinal enterococci.
A heterogeneous distribution of the colonies or the presence of abundant and different microorganisms can interfere with the differentiation of positive colonies.
Presentation
| Presentation | 30 prepared plates, 55 mm, for filtration purposes |
|---|---|
| Filling | 9 ± 1 mL |
| Packaging | 1 box containing 6 plastic bags with 5 plates of 55 mm/bag. |
Composition
| Ingredient | g/L |
|---|---|
| Tryptone | 17.00 |
| Peptone | 3.00 |
| Yeast extract | 5.00 |
| Bile | 10.00 |
| Sodium chloride | 5.00 |
| Esculin | 1.00 |
| Ammonium ferric citrate | 0.50 |
| Sodium azide | 0.15 |
| Agar | 15.00 |
Quality control
Physical/chemical control
| Color | Ochre yellow |
|---|---|
| pH | 7.1 ± 0.1 at 25 °C |
Microbiological control
Incubate the membrane filters (MF) with microorganisms in SB at 37 °C for 44 ± 4 h and transfer to BEA medium.
Aerobic. Incubation at 44 °C, for 2 h. Esculin test.
Microbiological control according to ISO 11133:2014/Amd 1:2018; A2:2020.
| Microorganism | Growth |
|---|---|
| Enterococcus faecalisATCC 19433 | Good - esculin positive reaction |
| Enterococcus faecalisATCC 29212, WDCM 00087 | Good - esculin positive reaction |
| Enterococcus faeciumATCC 6057 | Good - esculin positive reaction |
| Escherichia coliATCC 25922, WDCM 00013 | Inhibited |
| Aerococcus viridansATCC 11563, WDCM 00061 | Poor to good - esculin negative |
Sterility control
Incubation 48 hours at 30-35 °C and 48 hours at 20-25 °C: NO GROWTH.
Check at 7 days after incubation in same conditions.
Bibliography
- ATLAS, R.M. & J.W. SNYDER (1995) Handbook of Media for Clinical Microbiology. CRC Press. Boca Raton, Fla, USA.
- ALVAREZ, M.V., E. BOQUET, I. de FEZ (1988) Manual de Técnicas en Microbiologia Clínica. AEFA, San Sebastian.
- BRODSKY M.H. & D.A. SCHIEMANN (1976) Evaluation of Pfizer Selective Enterococcus and KF media for recovery of fecal streptococci from water by membrane filtration. Appl. Environ. Microbiol. 31:695-699.
- CHAPIN, K.C. & T-L. LAUDERDALE (2003) Chap. 27: Reagents, Stains and Media: Bacteriology in Manual of Clinical Microbiology 8th edition Volume 1, edited by Murray-Baron-Jorgensen-Pfaller-Yolken. ASM. Washington DC, USA.
- FORBES, B.A., D.F. SAHM, & A.S. WEISSFELD (1998) Bailey & Scott's Diagnostic Microbiology 10th edition. Mosby. St. Louis. USA.
- ISENBERG, H.D., D. GOLDBERG & J. SAMPSON (1970) Laboratory studies with a Selective Enterococcus Medium. Appl. Microbiol. 20:433.
- ISENBERG, H. D. (1992) Clinical Microbiology Procedures Handbook, Volume 1. ASM Press, Washington USA.
- ISO Standard 7899-2 (2000) Water Quality. Detection and enumeration of intestinal enterococci. Part 2: Membrane filtration method.
- ISO 11133:2014/Amd 1:2018/Amd 2:2020. Microbiology of food, animal feed and water. Preparation, production, storage and performance testing of culture media.
- MURRAY, P.R., E.J. BARON, J.H. JORGENSEN, M.A. PFALLER & R.H. YOLKEN (2003) Manual of Clinical Microbiology 8th Edition, Volume 1, ASM Press, Washington DC., USA.
- McFADDIN, J.F. (1985) Media for Isolation-Cultivation-Identification-Maintenance of Medical Bacteria. Volume 1. Williams & Wilkins. Baltimore. USA.
- PRATT-RIPPIN, K. & M. PEZLO (1992) Identification of Commonly Isolated Aerobic Grampositive Bacteria, in Clinical Microbiology Procedures Handbook, Volume 1 edited by H. D. Isenberg, ASM Press, Washington USA.
- RUOFF, K.L., R.A. WHILEY & D. BEIGHTON (2003) Chap. 29: Streptococcus in Manual of Clinical Microbiology 8th edition Volume 1, edited by Murray-Baron-Jorgensen-Pfaller-Yolken. ASM. Washington DC, USA.
- WINN, W. Jr., S. ALLEN, W. JANDA, E. KONEMAN, G. PROCOP, P. SCHRECKENBERGER, G. WOODS (2006) Koneman's Color Atlas and Textbook of Diagnostic Microbiology. 6th Edition. Lippincott Williams & Wilkins. Philadelphia. USA.
- UNE-EN ISO 11133 (2014). Microbiología de los alimentos para consumo humano, alimentación animal y agua - Preparación, producción, conservación y ensayos de rendimiento de los medios de cultivo.
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