Plot No. C40, Road No. 21Y, MIDC, Wagle Industrial Estate,
Thane(W)-400604, MH, India.
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Intended use
Recommended for isolation and presumptive identification of group D Streptococci from food and pharmaceutical products.
Composition**
| Ingredients | Gms/Litre |
|---|---|
| Peptone | 5.000 |
| HM peptone B # | 3.000 |
| Bile | 40.000 |
| Esculin | 1.000 |
| Ferric citrate | 0.500 |
| Agar | 15.000 |
Final pH (at 25°C) 6.6±0.2
**Formula adjusted, standardized to suit performance parameters
# Equivalent to Beef extract
Equivalent to Oxgall
Directions
Bile Esculin Agar is a ready to use solid media in glass bottle.The medium is pre-sterilized, hence it does not need sterilization. Medium in the bottle can be melted either by using a pre-heated water bath or any other method. Slightly loosen the cap before melting. When complete melting of medium is observed dispense the medium in tubes as butts /slants or in plates as desired and allow to solidify. If on plate, either streak, inoculate or surface spread the test inoculum (50-100 CFU) aseptically.
Principle And Interpretation
Group D Streptococci possess the group D lipoteichoic acid antigen in their cell walls. Former Group D species, which are predominant normal inhabitants of the human gastrointestinal tract, are termed as faecal Streptococci or Enterococci (8). The unique ability of Enterococci to split esculin was reported by Meyer and Schonfeld (10). Enterococci and Group D Streptococci hydrolyze esculin to esculetin and dextrose, which reacts with ferric citrate producing brownish black precipitate (9). The use of esculin hydrolysis in identification of Enterococci was first cited by Rochaix (12). Bile Esculin Agar was originally formulated by Swan (4) for the isolation and identification of Group D Streptococci from food. Facklam and Moody (2,5) further reported that using Bile Esculin Agar, Group D Streptococci could be differentiated from non-Group D Streptococci.
Bile Esculin Agar was also shown to aid differentiation of Enterobacteriaceae, Klebsiella, Enterobacter, Serratia from other Enterobacteriaceae genera (11) on the basis of esculin hydrolysis. However, other tests such as salt tolerance should be performed for identifying Enterococci (3).
The medium is highly nutritious. Peptone and HM peptone B serves as sources of carbon, nitrogen, amino acids, vitamins and essential growth nutrients. Bile inhibits most of the other accompanying bacteria. Esculin in the medium is hydrolyzed to esculetin and dextrose. Esculetin reacts with ferric citrate to form a dark brown or black complex, visualized as a zone of black precipitate around the colonies. If the media is dispensed in tubes in the form of slants, a positive reaction is indicated by blackening of more than half of the slant within 24-48 hours. If blackening is totally absent or if less than half of the slant is blackened within 24-48 hours, the test is negative. Viridians Streptococci sometimes exhibit a weak positive reaction. Also, Leuconostoc, Pediococcus, Lactococcus species causing human infections give a positive bile esculin test (6). To enhance the growth of Enterococci, Bile Esculin Agar can be supplemented with 50ml/L horse serum (9). Inoculate and incubate the test sample in Todd Hewitt Broth (M313). After 24 hours incubation add two drops of the culture onto the surface of slant or plate media (3, 9).
Type of specimen
Food samples
Specimen Collection and Handling:
For food and dairy samples, follow appropriate techniques for sample collection and processing as per guidelines (1,13,14). After use, contaminated materials must be sterilized by autoclaving before discarding.
Warning and Precautions
Read the label before opening the container. Wear protective gloves/protective clothing/eye protection/ face protection. Follow good microbiological lab practices while handling specimens and culture. Standard precautions as per established guidelines should be followed while handling specimens. Safety guidelines may be referred in individual safety data sheets.
Limitations :
- This medium is general purpose medium and may not support the growth of fastidious organisms.
Performance and Evaluation
Performance of the medium is expected when used as per the direction on the label within the expiry period when stored at recommended temperature.
Quality Control
Appearance
Sterile Bile Esculin Agar in glass bottle.
Colour of medium
Amber coloured medium
Quantity of medium
500 ml of medium in glass bottle.
Reaction
6.40-6.80
Sterility Test
Passes release criteria
Cultural Response
Cultural characteristics observed in an increased atmosphere of Carbon dioxide after an incubation at 35-37°C for 18-24
hours.
| Organism | Inoculum (CFU) | Growth | Recovery | Esculin Hydrolysis |
|---|---|---|---|---|
| Enterococcus faecalis ATCC 50-100 29212 (00087*) | luxuriant | >=50% | positive reaction, blackening of medium around the colony | |
| Proteus mirabilis ATCC 50-100 25933 | luxuriant | >=50% | negative reaction | |
| Streptococcus pyogenes 50-100 ATCC 19615 | none-poor | <=10% | negative reaction |
Key: *Corresponding WDCM numbers.
Storage and Shelf Life
On receipt store between 15-25°C. Use before expiry date on the label. Product performance is best if used within stated expiry period.
Disposal
User must ensure safe disposal by autoclaving and/or incineration of used or unusable preparations of this product. Follow established laboratory procedures in disposing of infectious materials and material that comes into contact with sample must be decontaminated and disposed of in accordance with current laboratory techniques (6,7).
| Product Name | Bile Esculin Agar |
|---|---|
| SKU | SM972D |
| Customized Product Available | No |
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