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Columbia agar | Principle | Composition | Reading
Ⅰ. Overview
Décrit à l'origine comme une base de gélose nutritive à usage général par Ellner en 1966 à l'Université de Columbia. Gélose Columbia est un milieu très nutritif permettant la culture et l’isolement d’une grande variété de microorganismes.
Originally described as a general purpose nutrient agar base by Ellner in 1966 at Columbia University. Columbia agar is a highly nutritious medium for the cultivation and isolation of a wide variety of microorganisms.
Since dehydrated media became available, the 2 most frequently used basic types of blood agar are casein hydrolyzate and meat infusion media. Columbia agar combines the virtues of these two types of medium to give an improved overall performance.
By adding blood, selective agents or growth accelerators, it is possible to prepare a wide variety of media suitable for specific uses.
Columbia agar
Ⅱ. Composition of Columbia agar
Suspend the components, dehydrated powder, in water (42.5 grams in 1000 ml of purified/distilled water). The medium is boiled for a few seconds until the ingredients are completely dissolved. Distribute in tubes or bottles and sterilize by autoclaving at 121°C for 15 minutes.
Composition of Columbia agar |
|||
|---|---|---|---|
| Ingredients | gram/litre | Ingredients | gram/litre |
| Pancreatic casein digestion | 12g | Peptic digestion of animal tissue | 5.0g |
| Yeast extract | 3.0g | Beef extract | 3g |
| Cornstarch | 1g | sodium chloride | 5g |
| Agar | 13.5g | pH final | 7,3 ± 0,2 |
Ⅲ. Preparation from Columbia Agar Base
🏼 With the Columbia base, it is possible to prepare the following media::
- Preparation of the blood agar : at 45°C, mix homogeneously 5 to 10% sterile defibrinated blood, after shaking, avoiding including air bubbles, distribute in Petri dishes. It allows to determine haemolytic reactions.
- Preparation of cooked blood agar (chocolate) : Add 5% sterile blood. Heat the mixture in a bain-marie for about 10 minutes at 80°C, stirring all the time, until the medium turns chocolate brown, divide into Petri dishes.
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Blaser–Wang Campylobacter medium preparation : Columbia agar (890mL) + Sheep blood (100mL) + Antibiotic supplement 10ml (Cephalothin, Vancomycin, Trimethoprim, Amphotericin B, Polymyxin B).
Note : In the same way: Karmali's Campylobacter medium and Butzler's Campylobacter medium. - Columbia Agar Base can be used to prepare Milk Lactose and Egg Yolk Emulsion Agar for the isolation of fastidious clostridia
- Selective medium for Gardnerella vaginalis and Medium for Haemophilus ducreyi.
🏼 Autres applications :
- CAMP Test
- Nagler Test
- Elek Test
Alpha hemolysis
Beta hemolysis
CAMP TEST