Dehydrated culture media
Salt Egg Yolk Agar Base
For the isolation of pathogenic staphylococci.
- Cat. No.
- LC-1326
- Category
- Dehydrated culture media
- Format
- 500 g
- Storage
- 2 to 25 °C
- Minimum guaranteed shelf life
- 15 months
Salt Egg Yolk Agar Base is a medium used for the isolation of pathogenic staphylococci.
Key features
Applications
Differentiation of Staphylococcus.
Preparation
110 g in one liter of distilled water; sterilize at 121 °C for 15 minutes, then add the egg yolk solution and the calcium chloride.
Principles and uses
Infusion Heart Broth provides nitrogen, vitamins, minerals and amino acids essential for growth. Lithium chloride is the selective agent that inhibits most microorganisms other than staphylococci. D-mannitol is the carbohydrate energy source. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Bacteriological agar is the solidifying agent.
Technical specifications
| Solubility | Without residues |
|---|---|
| Appearance | Fine powder |
| Color of the dehydrated medium | Beige |
| Color of the prepared medium | Red |
| Final pH (25 °C) | 7.3 ± 0.2 |
| Amount per litre | 110 g |
| Storage | 2 to 25 °C |
Formula
| Ingredient | g/L |
|---|---|
| Bacteriological agar | 15 |
| D-mannitol | 10 |
| Sodium chloride | 55 |
| Lithium chloride | 5 |
| Infusion Heart Broth | 25 |
Typical formula in g/L, adjusted and/or supplemented as required to meet performance criteria.
Preparation and use
Preparation
Suspend 110 grams of the medium in one liter of distilled water. Mix well. Dissolve by heating with frequent agitation until boiling. Sterilize at 121 °C for 15 minutes. Allow to cool to 55 °C and add 100 mL of a sterile 50% egg yolk solution and 10 mL of 1 M calcium chloride. Homogenize and pour into Petri dishes.
Instructions for use
Inoculate the sample on the plate and incubate at 37 °C for 24-40 hours. Coagulase-positive staphylococci form clear yellow colonies. After 20 to 40 hours of incubation the colonies start turning the medium opaque in ring shape from the lower part of the colonies. When incubated for 18-24 hours, pearly rings are formed around the colonies on the medium, similar to oil drops upon the water surface. Therefore, even the pearly rings alone serve as a means of differentiation of coagulase-positive staphylococci. Colonies of coagulase-negative staphylococci are rather opaque and do not opacify the medium nor form pearly rings.
Quality control
Microbiological test
Incubation conditions: 35 ± 2 °C / 18-24 h.
| Microorganism | Specification |
|---|---|
| Staphylococcus epidermidisATCC 12228 | Acceptable growth |
| Klebsiella aerogenesATCC 13048 | Inhibited growth |
| Staphylococcus epidermidisATCC 14990 | Good growth |
| Escherichia coliATCC 25922 | Inhibited growth |
| Staphylococcus aureusATCC 25923 | Good growth |
Bibliography
- Baird-Parker, A.C. 1962. An improved diagnostic and selective medium for isolating coagulase-positive staphylococci. J. Appl. Bacteriol. 25: 12-19.
- MacFaddin, J.F. 1985. Media for the isolation-cultivation-maintenance of medical bacteria. Volume 1. Williams and Wilkins, Baltimore, London.
What you receive
The product
Shipped under controlled temperature when the product requires it.
Lot certificate
Every lot comes with its certificate.
Tracked shipment
Follow your shipment live, from our warehouse to your lab.
Other products in the same category
Frequently asked questions
Can I ask for formats other than those listed?
Yes: custom formats and OEM packs are available on request. Tell us the quantities you need.
How do I see the prices?
Prices are shown after you sign in to the customer area, with your account discount already applied.
How long does delivery take?
We give you the availability with the quote, within 24 hours of your request.