Soyabean Bile Broth Base

Intended Use

Recommended for enrichment and isolation of Escherichia coli O157: H7.

Composition**

Final pH (at 25°C): 7.3±0.2

**Formula adjusted, standardized to suit performance parameters

Directions

Suspend 32.62 grams in 1000 ml purified / distilled water. Heat if necessary to dissolve the medium completely. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. Cool to 45-50°C and aseptically add rehydrated contents of 1 vial of NO 20 Selective Supplement (FD290). If desired, aseptically add rehydrated contents of 1 vial of CCV Supplement (FD247) for isolation of Escherichia coli O157 from foods. Mix well and dispense as desired.

Principle And Interpretation

Soyabean Bile Broth Base is formulated as recommended by FDA (1) for the enrichment and isolation of E. coli O157:H7. Tryptone and soya peptone provide carbonaceous, nitrogenous compounds and other essential growth nutrients. Dextrose is the fermentable carbohydrate and energy source. Bile salts mixture inhibits gram-positive bacteria. Sodium chloride maintains osmotic equilibrium while phosphate buffers the medium well. Novobiocin renders the medium selectivity. Whenever low levels of E. coli O157:H7 are suspected, the food is enriched in Soyabean Bile Broth and further plated on selective medium as Sorbitol MacConkey Agar (M2981) or Hemorrhagic coli (HC) Agar (M1158) for isolation and identification.

Type of specimen

Clinical samples - Stool samples; Food samples.

Specimen Collection and Handling

Blend 25 grams food sample to be tested in 224 ml Soyabean Bile Broth and incubate with shaking (about 100 rpm) at 37° C for 18-24 hours. Prepare dilution of the enrichment culture with phosphate buffer and spread 0.1 ml of each dilution on HC Agar or Sorbitol MacConkey Agar (M2981) plates and incubate at 43°C for 24 hours. After use, contaminated materials must be sterilized by autoclaving before discarding.

Warning and Precautions :

In Vitro diagnostic Use. For professional use only. 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 clinical specimens. Safety guidelines may be referred in individual safety data sheets

Limitations :

1. Individual organisms differ in their growth requirement and may show variable growth patterns on the medium.
2. Each lot of the medium has been tested for the organisms specified on the COA. It is recommended to users to validate the medium for any specific microorganism other than mentioned in the COA based on the user's unique requirement.
3. Enriched sample must be plated onto Sorbitol MacConkey Agar (M2981) and biochemical and serological tests must be performed for confirmation.

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: Cream to yellow homogeneous free flowing powder

Colour and Clarity of prepared medium: Light amber coloured clear solution

Reaction: Reaction of 3.26% w/v aqueous solution at 25°C. pH: 7.3±0.2

pH: 7.10-7.50

Cultural Response

Cultural characteristics observed after an incubation at 35-37°C or 41.5°C for 18-48 hours with added NO 20 Selective Supplement (FD290) and if desired CCV Supplement (FD247). Recovery done on Sorbitol MacConkey Agar(M2981).

Key *: Corresponding WDCM numbers

Storage and Shelf Life

Store between 10-30°C in a tightly closed container and the prepared medium at 2-8°C. Use before expiry date on the label. On opening, product should be properly stored dry, after tightly capping the bottle in order to prevent lump formation due to the hygroscopic nature of the product. Improper storage of the product may lead to lump formation. Store in dry ventilated area protected from extremes of temperature and sources of ignition Seal the container tightly after use. 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 clinical sample must be decontaminated and disposed of in accordance with current laboratory techniques (2,3).

Reference

1. FDA Bacteriological Analytical Manual, 2005, 18th Ed., AOAC, Washington, D.C.
2. Isenberg, H.D. Clinical Microbiology Procedures Handbook 2nd Edition.
3. Jorgensen, J.H., Pfaller, M.A., Carroll, K.C., Funke, G., Landry, M.L., Richter, S.S and Warnock., D.W. (2015) Manual of Clinical Microbiology, 11th Edition. Vol. 1.