COLUMBIA CNA SEMI-SELECTIVE AGAR
W/ 5% SHEEP BLOOD

Technical Data #1019a / 2013.04.22

Columbia CNA Semi Selective Agar w/ 5% sheep blood is a selective solid medium for the isolation of Gram-positive micro-organisms from clinical and nonclinical specimens. Antimicrobial agents, colistin and nalidixic acid, suppress growth of gram-negative organisms. The addition of blood permits the interpretation of hemolytic activities.

 


 

FORMULA
in grams per liter purified filtered water

Casein Peptone

10,0

Meat Peptone

5,0

Yeast Extract

5,0

Beef Extract

3,0

Corn Starch

1,0

Sodium Chloride

5,0

Agar

13,5

Colistin

0,005

Nalidixic Acid

0,0075

Defibrinated Sheep Blood

50 ml

pH 7,3 +/- 0,2 25 C

This approximate formula may be adjusted and/or enriched to obtain best results.


PRECAUTIONS
This medium is for IN VITRO diagnostic use only.


STORAGE
Store prepared media at 2-8 C protected from direct light and dehydrated powder, in a dry place, in tightly-sealed containers at 2-25 C.


SIGN OF DETERIORATION
Media should not be used if the expiry date has passed. Prepared media should not be used if there are signs of contamination or deterioration (shrinking, cracking, evaporation or discoloration). Do not use dehydrated media if it is caked.


DIRECTIONS
Suspend 42,5 g of dehydrated media in 950 ml of purified filtered water. Heat with frequent agitation and boil for one minute. Sterilize at 121 C for 15 minutes. Cool to 45-50 C and aseptically add 50 ml of Defibrinated Sheep Blood (4245) and 5 ml of CNA Supplement (8735). Mix gently and dispense into sterile Petri dishes.


PROCEDURE
Prior to inoculate, the prepared media should be brought to room temperature.

  1. Directly, inoculate plate as soon as possible with specimen and streak for isolation. Several stabs are recommended to be done in blood plate.
  2. Incubate at 35 C under 5-10% CO2 for 24-48 hours.


QUALITY CONTROL

Results after 24 hrs at 35C with CO2

Organisms

ATCC

Growth

Hemolysis

Streptococcus pyogenes

19615

+

beta

Streptococcus pneumoniae

6305

+

alpha

Staphylococcus aureus

25923

+

 
Escherichia coli

25922

- or partial

 
Proteus mirabilis

12453

- or partial

 


LIMITATIONS OF METHOD
This medium is only a part of the identification. Other tests may be required.


REFERENCES

  1. N.C.C.L.S. Quality Assurance for Commercially prepared Microbiological Culture Media. N.C.C.L.S. Publication M-22-A Approved Standard 1990 Vol. 10 No.14.
  2. Lennette, E.H., Ballows, A., Hausler, W.J.Jr., and Shadomy, H.J. Manual of Clinical Microbiology. 4th ed. 1985 Washington D.C.: American society for Microbiology.
  3. Mac Faddin, Jean F., Media for Isolation-Cultivation-Identification-Maintenance of Medical Bacteria Vol.1 1985 Baltimore, MD. Williams & Wilkins.


CATALOGUE NUMBERS

Dehydrated media 500 g QB-39-1006
     
Prepared media    
Plates, 100x15 mm 10/pkg 1019
Mono-Plates, 100x15 mm 10/pkg 1019M
Defibrinated Sheep Blood 50 ml 4245
CNA Supplement 10x5 ml 8735


 





 

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