CRITERION™ AZIDE BLOOD AGAR BASE

Cat. no. C5040 CRITERION™ Azide Blood Agar Base 66gm
Cat. no. C5041 CRITERION™ Azide Blood Agar Base 500gm
Cat. no. C5042 CRITERION™ Azide Blood Agar Base 2kg
Cat. no. C5043 CRITERION™ Azide Blood Agar Base 10kg
Cat. no. C5044 CRITERION™ Azide Blood Agar Base 50kg

INTENDED USE

Hardy Diagnostics CRITERION™ Azide Blood Agar Base is used for isolation of streptococci and staphylococci. Blood may be added for the determination of hemolytic reactions.

This dehydrated culture medium is a raw material intended to be used in the making of prepared media products, which will require further processing, additional ingredients, or supplements.

SUMMARY

CRITERION™ Azide Blood Agar Base is used for the isolation of gram-positive organisms from both clinical and non-clinical specimens. Edwards, in 1933, used a selective broth containing crystal violet and sodium azide in the isolation of mastitis streptococci. (1) Snyder and Lichstein added 0.01% sodium azide to prevent the swarming of Proteus species and also permitted the isolation of streptococci from mixed bacterial populations. (3,7) Edwards' medium was modified by Packer by preparing Infusion Blood Agar with 1:15,000 sodium azide and 1:500,000 crystal violet for the study of bovine mastitis. (6) Mallmann, Botwright and Churchill reported there was a bacteriostatic effect on gram-negative bacteria when sodium azide is present. (4) The Azide Blood Agar Base formula was based on the work of these researchers.

Beef extract and tryptose serve as sources of carbon, nitrogen, vitamins and minerals. Sodium chloride is added to maintain the osmotic equilibrium. Sodium azide inhibits cytochrome oxidase in gram-negative bacteria. CRITERION™ Azide Blood Agar Base can be supplemented with 5-10% sheep, rabbit, or horse blood for the isolation, cultivation and determination of hemolytic reactions of fastidious pathogens.

FORMULA*

Gram weight per liter: 33.0gm/L
Casein Peptone 5.0gm
Meat Peptone 5.0gm
Sodium Chloride 5.0gm
Beef Extract 3.0gm
Sodium Azide 0.2gm
Agar 15.0gm

Final pH 7.2 +/- 0.2 at 25ºC.

* Adjusted and/or supplemented as required to meet performance criteria.

STORAGE AND SHELF LIFE

Store the sealed bottle(s) containing dehydrated culture medium at 2-30ºC. Protect dehydrated culture media from moisture and light. Keep container tightly closed, dehydrated medium is very hygroscopic. The dehydrated culture media should be discarded if it is not free flowing and homogenous or if the color has changed from its original tan color.

Store the prepared media at 2-8ºC.

PRECAUTIONS

METHOD OF PREPARATION FOR DEHYDRATED CULTURE MEDIA

1. Suspend 33.0gm of the dehydrated culture media in 1 liter of distilled or deionized water.

2. Heat to boiling to dissolve completely.

3. Autoclave at 121ºC. for 15 minutes.

4. To prepare blood agar, aseptically add 5% sterile defibrinated blood to the medium at 45-50ºC. Mix well.

PROCEDURE AND INTERPRETATION OF RESULTS

For information on procedures and interpretation of results, consult listed references.

LIMITATIONS

Hemolytic patterns of streptococci grown on Azide Blood Agar are somewhat different than those seen on ordinary blood agar. The sodium azide enhances hemolysis. (6)

Hemolytic patterns may vary with the source of animal blood or base medium used. (5)

MATERIALS REQUIRED BUT NOT PROVIDED

Standard microbiological supplies and equipment such as autoclaves, incubators, etc., are not provided.

QUALITY CONTROL

Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Staphylococcus aureus
ATCC ® 25923
A 24-48hr 35°C Aerobic Growth; beta-hemolysis
Streptococcus pneumoniae
ATCC ® 6305
A 24-48hr 35°C Aerobic Growth; alpha-hemolysis
Streptococcus pyogenes
ATCC ® 19615
A 24-48hr 35°C Aerobic Growth; beta-hemolysis
Escherichia coli
ATCC ® 25922
B 24-48hr 35°C Aerobic Inhibited

User Quality Control

PHYSICAL APPEARANCE

CRITERION™ Azide Blood Agar Base powder should appear homogeneous, free-flowing and tan in color. The prepared media should appear slightly opalescent without precipitate, and light to medium amber in color. When prepared with 5% sheep blood the media should appear opaque, and cherry red in color.

REFERENCES

1. Edwards, S.J. 1933. The diagnosis of Streptococcus mastitis by cultural methods. J. Comp. Pathol. Ther.; 46:211.

2. Isenberg, H.D. Clinical Microbiology Procedures Handbook, Vol. I, II & III. American Society for Microbiology, Washington, D.C.

3. Lichstein, H.C. and M.L. Snyder. 1941. The inhibition of the spreading growth of Proteus and other bacteria to permit the isolation of associated streptococci. J. Bacteriol.; 42:653.

4. Mallmann, Botwright, and Churchill. 1943. J. Bacteriol.; 46:343.

5. Jorgensen., et al. Manual of Clinical Microbiology, American Society for Microbiology, Washington, D.C.

6. Packer, R.A. 1943. The use of sodium azide (NaN3) as an inhibition substance of gram-negative bacteria. J. Infect. Dis.; 67:113.

7. Snyder, M.L. and H.C. Lichstein. 1940. Sodium azide as an inhibition substance of gram-negative bacteria. J. Infect. Dis.; 67:113.


ATCC is a registered trademark of the American Type Culture Collection.

050916gr