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AZIDE DEXTROSE BROTH

 

Selective medium for the detection of Enterococci in water and sewage.

 

Code: CB1/3052

 

Typical formula g/l

 

Peptone mix

15.0
Beef extract 4.5
Glucose 7.5
Sodium chloride

7.5

Sodium azide     0.2

 

Final pH 7.2 +/-0.2

 

Directions

Suspend 34.7g of Azide Dextrose Broth in 1000 ml of cold distilled water. Heat gently to dissolve, distribute into 10ml tubes and sterilise by autoclaving at 121C for 15 minutes. For inocula of more than 1ml per 10ml medium prepare Azide Dextrose Broth at double or multiple concentration.

 

WARNING: see hazardous precautions for media containing azide.

 

Description

Azide Dextrose Broth is a selective medium for the detection of enterococci in water and sewage; its composition is in accordance with WHO specifications.

 

In use

The enumeration of enterococci is carried out in tubes, according to the method of the most probable number (MPN); vary the amount of inoculum (in multiples or fractions of 1ml) depending on the type of specimen prepa­ring at least five tubes of each dilution. As a liquid dilution, use a phosphate buffer or else a 0.5% aqueous peptone solution (w/v). Incubate at 35C for 24 hours, and obser­ve if growth has occurred; if not, continue incubation for a further 24 hours. Calculate the result using the appropriate tables, and express it as the most probable presumptive number. Confirm the presumptive result with a subculture in Ethyl Violet Azide Broth.

 

User quality assurance (37C-24 h)

 

Productivity control

E.faecalis  ATCC 19433: good growth

 

Selectivity control

E.coli ATCC 25922: inhibited

 

Storage

Dehydrated media: 15-30C

User prepared tubes: 1 month at 2-8C

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