Plot No. C40, Road No. 21Y, MIDC, Wagle Industrial Estate,
Thane(W)-400604, MH, India.
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Intended Use
With the addition of selective reagent used for the isolation of Salmonella Typhi
Composition
| Ingredients | g/L |
|---|---|
| HiVeg™ special peptone | 10.000 |
| HiVeg™ extract | 5.000 |
| Dextrose (Glucose) | 10.000 |
| Sodium chloride | 5.000 |
| Agar | 30.000 |
| Final pH (at 25°C) | 7.3±0.2 |
Formula adjusted, standardized to suit performance parameters
Directions
Suspend 60.0 grams in 1000 ml purified/distilled water. Heat to boiling to dissolve the medium completely. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. Cool to 45-50°C. To sterile molten base, add 4 ml of 1% Brilliant green solution and 70 ml of selective reagent.
Selective Reagent
- Solution 1: 40 gm sodium sulphite in 100 ml distilled water.
- Solution 2: 21 gm dibasic sodium phosphate in 100 ml distilled water.
- Solution 3: 12.5 gm bismuth ammonium citrate in 100 ml distilled water.
- Solution 4: 0.96 gm ferrous sulphate in 20 ml distilled water with 2 drops of hydrochloric acid.
Prepare each solution separately and then combine. Boil the combined solution until a slate grey colour develops. Mix well and pour into sterile Petri plates.
Principle And Interpretation
Salmonella is a genus of gram-negative Enterobacteriaceae- commonly implicated in foodborne illness and the causative agent of typhoid and paratyphoid fever. Salmonella species have been isolated from humans and animals. More than 2000 serovars of Salmonella exists with each showing different host specificities. For example, humans are the only known natural reservoir for serotype Salmonella Typhi and serotypes Salmonella Paratyphi A, B and C (1).The organism can be transmitted by the faecal-oral route. It is excreted by humans in faeces and may be transmitted by contaminated water, food, or by person-to-person contact (with inadequate attention to personal hygiene). Wilson and Blair Agar, formulated by Wilson and Blair (2) is recommended for isolating Salmonella species especially Salmonella Typhi from clinical specimens. The selective reagent formulation is a modification of the bismuth sulphite reagent described by Hajna and Perry (3). This medium is particularly valuable for the isolation of S. Typhi. The medium is highly selective for Salmonella, being inhibitory to coliforms, Proteus and Shigella; occasional strains of coliforms grow to form dull green or brown colonies, but without a surrounding metallic sheen. The medium is also suitable for the isolation of lactose-fermenting strains of Salmonella (which can not be differentiated on lactose containing differential media) since lactose is not the fermentable substrate used in this medium. Wilson Blair HiVeg™ Agar Base is prepared by using vegetable peptones in place of animal based peptones which make the media free of BSE/TSE risks. HiVeg™ special peptone and HiVeg™ extract provide nitrogenous, carbonaceous compounds and other growth nutrients. Brilliant green dye inhibits all gram-positive bacteria. Dextrose is the fermentable carbohydrate. Ferrous sulphate aids in H2S production. Bismuth is a heavy metal, which is inhibitory to most gram-negative enteric bacilli other than Salmonella. Ferrous sulphate is reduced by Salmonella species in presence of bismuth sulphite and dextrose to form iron sulphide, indicated by black coloured colonies. Disodium hydrogen phosphate buffers the medium well. Sodium chloride balances the osmotic equilibrium.
Type of specimen
Food and dairy samples; Water samples.
Specimen Collection and Handling
For food and dairy samples, follow appropriate techniques for sample collection and processing as per guidelines (4,5,6). For water samples, follow appropriate techniques for sample collection, processing as per guidelines and local standards.(7) 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
- Do not store the medium in refrigerator (4°C) for longer than 2 days, as the medium changes to green colour and reduces its selectivity.
- Further biochemical and serological tests need to be carried out 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
Gelling: Firm, comparable with 3.0% Agar gel.
Colour and Clarity of prepared medium: Basal Medium: Light yellow coloured clear to slightly opalescent gel. After addition of the selective reagent and 1%Brilliant green, greenish yellow coloured, opaque gel forms in Petri plates.
Reaction: Reaction of 6.0% w/v aqueous solution at 25°C. pH: 7.3±0.2
pH: 7.10-7.50
Cultural Response
Cultural characteristics observed with added 1% Brilliant green and selective reagents after an incubation at 35-37°C for 24-48 hours.
| Organism | Inoculum (CFU) | Growth | Recovery | Colour of colony |
|---|---|---|---|---|
| Escherichia coli ATCC 25922 (00013*) | >=104 | inhibited | 0% | |
| Proteus mirabilis ATCC 25933 | 50-100 | luxuriant | >=50% | green |
| Salmonella Typhi ATCC 6539 | 50-100 | luxuriant | >=50% | black with sheen |
| Salmonella Typhimurium ATCC 14028 (00031*) | 50-100 | luxuriant | >=50% | black with sheen |
Key: *Corresponding WDCM numbers.
Storage and Shelf Life
Store between 10-30°C in a tightly closed container and the prepared medium at 20-30°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 sample must be decontaminated and disposed of in accordance with current laboratory techniques (8,9).
| Product Name | Wilson Blair HiVeg™ Agar Base |
|---|---|
| SKU | MV331 |
| Product Type | HiVeg™ |
| Physical Form | Powder |
| Origin | Animal Free (Veg) |
| Packaging type | HDPE |
| References | 1. Murray P. R., Baron J. H., Pfaller M. A., Jorgensen J. H. and Yolken R. H., (Ed.), 2003, Manual of Clinical Microbiology,8th Ed., American Society for Microbiology, Washington, D.C. 2.Wilson W. J. and Blair E. M., 1926, J. Pathol. Bacteriol., 29 : 310. 3.Hajna A. A. and Perry C. A., 1938, J. Lab. Clin. Med., 23:1185. |
| Customized Product Available | No |
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