Cat. no. K86 Azide Dextrose Broth (SS), 20x125mm Tube, 10ml 20 or 100 tubes/box
Cat. no. K87 Azide Dextrose Broth (DS), 20x125mm Tube, 10ml 20 or 100 tubes/box


Hardy Diagnostics Azide Dextrose Broth is used to detect the presence of fecal streptococci in water, shellfish, sewage and milk.

This product is not intended to be used for the diagnosis of human disease.


Azide Dextrose Broth is recommended by the APHA for the isolation of fecal streptococci. (7) Rothe, at the Illinois State Health Department, originated the formula for Azide Dextrose Broth. (12) Mallmann and Seligmann conducted a comparative study to investigate the detection of streptococci in water and wastewater using Azide Dextrose Broth. (13) Their work supported use of the medium in determining the presence of streptococci in water, wastewater, shellfish and other materials. Azide Dextrose Broth has also been used for isolation of streptococci in foodstuffs and other specimens of sanitary significance as an indication of contamination.

Beef extract, pancreatic digest of casein and peptic digest of animal tissue serve as sources of carbon, nitrogen, vitamins and minerals. Dextrose serves as an energy source and sodium chloride is added to maintain the osmotic equilibrium. Sodium azide inhibits cytochrome oxidase in gram-negative bacteria. As the concentration of ingredients in Azide Dextrose Broth is critical to the media performance, it is recommended that samples of 10ml or larger use the Double Strength (DS) formulation to prevent dilution of the ingredients. Hardy Diagnostics Azide Dextrose Broth (DS) formulation contains the same ingredients as the Single Strength (SS) formulation, however, it does contain twice the amount of ingredients per liter of deionized water.


Ingredients per liter deionized water:*

Azide Dextrose Broth (SS):
Casein Peptone 7.5gm
Animal Tissue Peptone 7.5gm
Dextrose 7.5gm
Sodium Chloride 7.5gm
Beef Extract 4.5gm
Sodium Azide 0.2gm

Azide Dextrose Broth (DS) contains twice the amount of the above listed ingredients per liter of deionized water.

Final pH 7.2 +/- 0.2 at 25ºC.

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


Storage: Upon receipt store at 2-8ºC. away from direct light. Media should not be used if there are any signs of deterioration (shrinking, cracking, or discoloration), hemolysis, contamination, or if the expiration date has passed. Product is light and temperature sensitive; protect from light, excessive heat, moisture, and freezing.



Azide Dextrose Broth is used to detect presumptive evidence of fecal contamination. Further biochemical testing must be done for confirmation.

For inoculum sizes of 10ml or larger, the use of Double Strength (DS) medium (Cat. no. K87) is recommended to prevent further dilution of the ingredients.


Specimen Collection: Consult listed references for information on specimen collection.

Method of use as described for water and wastewater testing:

1. Inoculate a series of Azide Dextrose Broth tubes with appropriately graduated quantities of sample. Use sample quantities of 10ml or less. Use the Double Strength (DS) broth for 10ml inocula. Consult appropriate references for suggested sample sizes. (2-6)

2. Incubate inoculated tubes at 35 +/- 2.0ºC. for 20 to 48 hours.

3. Examine each tube for turbidity at the end of 24 +/- 2.0 hours. If no turbidity is evident, reincubate and read again at the end of 48 +/- 3.0 hours.


A positive test is indicated by turbidity (cloudiness) in the broth. A negative test remains clear.

All Azide Dextrose Broth tubes showing turbidity after 24 or 48 hours incubation must be subjected to the Confirmed Test Procedure. Consult appropriate references for details of the Confirmed Test Procedure and further identification of Enterococcus . (2)


Standard microbiological supplies and equipment such as loops, other culture media, swabs, applicator sticks, incinerators, and incubators, etc., as well as serological and biochemical reagents, are not provided.


Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Enterococcus faecalis
ATCC ® 29212
A 18-48hr 35°C Aerobic Heavy growth
Escherichia coli
ATCC ® 25922
B 18-48hr 35°C Aerobic Inhibited

User Quality Control


E. faecalis growing in Azide Dextrose Broth, SS

Enterococcus faecalis (ATCC ® 29212) growing in Azide Dextrose Broth, SS (Cat. no. K86). Incubated aerobically for 24 hours at 35ºC.

E. coli inhibited in Azide Dextrose Broth, SS

Escherichia coli (ATCC ® 25922) inhibited in Azide Dextrose Broth, SS (Cat. no. K86). Incubated aerobically for 24 hours at 35ºC.


1. MacFaddin, J.F. 1985. Media for Isolation , Cultivation , Identification , Maintenance of Bacteria , Vol. I. Williams & Wilkins, Baltimore, MD.

2. U.S. Food and Drug Administration. Bacteriological Analytical Manual. AOAC, Arlington, VA.

3. American Public Health Association. Standard Methods for the Examination of Dairy Products, APHA, Washington, D.C.

4. APHA Technical Committee on Microbiological Methods for Foods. Compendium of Methods for the Microbiological Examination of Foods, APHA, Washington, D.C.

5. American Public Health Association. Standard Methods for the Examination of Water and Wastewater, APHA, Washington, D.C.

6. The Official Compendia of Standards. 2008. USP27-NF22 . United States Pharmacopeial Convention, Rockville, MD.

7. Rothe. 1948. Illinois State Health Department.

8. Mallmann, W.L. and E.B. Seligmann. 1950. A comparative study of media for the detection of streptococci in water and sewage. Am. J. Public Health ; 40:286.

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