st1:City>COLUMBIA AGAR BASE

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A general purpose nutritious agar base for the preparation of enriched media when sterile blood is added.

 

Code: CB1/1021

 

Typical formula g/l

 

Peptone mix	10.0
Tryptose	10.0
Peptone	3.0
Maize starch	1.0
Sodium chloride	5.0
Agar	13.0

 

pH: 7.3 +/- 0.2

 

Directions

Suspend 42 g in 1000ml of cold distilled water; heat to boiling and sterilise in the autoclave at 121^°C for 15 minutes. Cool to 50°C and add the suitable enrichment supplement.

  

Description

Elmer et al. of the Columbia University, found that the combination of meat and ca­sein peptones used, gave better results than those obtained with current blood agar bases: it affords a more rapid and abundant growth of streptococci, staphylococci, Neisseria and Haemophi­lus, with better defined haemolytic reactions. Columbia Agar Base can be used as it is, for the cultivation of bacteria, which are not particularly fastidious, or else enriched in various ways:

1.   Blood agar: add 5 % sterile defibrinated sheep or horse blood to the base which has been sterilised and cooled in a water bath to 50^°C; mix thoroughly and pour into sterile plates.

2.   Chocolate agar: add 10% sterile defibrinated sheep or horse blood to the base which has been sterilised and cooled in a water bath to 50^°C, heat to 80^°C for 10 minutes with constant stirring, cool to 50^°C and pour into sterile plates.

3.   Serum agar: add 20% serum to the base, which has been ste­rilised and cooled in a water bath to 50^°C. Mix and pour into ste­rile plates. The medium, thus prepared serves as a virulence test for Corynebacterium diphtheriae, using the Elek diffusion techni­que.

4.   Lactose egg yolk milk agar: suspend 41 grams of Columbia Agar Base in 1000 ml of distilled water. Add 12g of lactose, 1g of agar and 3.25ml of a 1% solution of Neutral Red; heat to boi­ling stirring constantly. Adjust pH to 7.0 and sterilise by auto­claving at 121^°C for 15 minutes. Cool in a temperature-regulated water bath to 50^°C, and aseptically add 150ml of sterile skim milk and 36ml of sterile egg yolk emulsion. Mix thoroughly and pour into sterile plates. The prepared medium consequently allows for the identification of clostri­dia on the basis of lactose utilisation, lecithinase and lipase pro­duction and proteolytic activity. The addition of 180μg/ml of neo­mycin sulphate and 240μg/ml of sodium azide make the me­dium selective for clostridia.

5.   Campylobacter Media: add to 500ml of the pre-cooled base, 10% defibrinated or lysed horse or sheep blood and the content of one vial of Baser Wang Antimicrobic Supplement or other sui­table selective supplements.

 

User quality assurance (Columbia Blood Agar Base + 5% def.blood) (37°C-24 h)

 

Productivity control

S.pyogenes ATCC 19615: good growth, β-haemolysis

S.pneumoniae ATCC 6303: good growth, α-haemolysis

S.aureus ATCC 25923: good growth

E.coli ATCC 25922: growth

 

 

Storage

Dehydrated media: 15-30°C

User prepared plates: 1 month at 2-8°C

 

Reference

Ellner, P.D. Stoessel, C.J. Drakeford, E. & Vasi, F. (1966. Am. J. Clin. Path. 45, 502-504.