CLED DI Medium (Bevis)

Description

Use and description:

A dehydrated culture medium recommended for the isolation and enumeration of urinary microorganisms. Due to the presence of bromothymol blue, lactose-fermenting bacteria are detected by producing yellow halo around colonies. An additional dye, acid fuchsin cause lactose fermenting bacteria to produce pink colonies, non-fermenting species are colourless. It is electrolyte deficient to prevent the swarming of Proteus sp. Cystine helps the growth of coliforms.

Composition per litre:

Peptones…………….…………………………….10.000 g

L-cystine……………………………………………..0.128 g

Acid fuchsin…………………………………….… 0.100 g

Beef extract………………………………………..3.000 g

Lactose……………………………………………..10.000 g

Bromothymol blue………………………..……0.020 g

Agar………………………………………………….14.000 g

Final pH of the ready to use medium: 7.5 +/- 0.2

Medium preparation:

Add 37.2 grams of dehydrated culture medium to 1 litre of distilled water. Heat with repeated stirring and boil for one minute to dissolve completely. Autoclave at 121°C for 15 minutes cool down and distribute.

Quality specifications:

Dehydrated medium: homogeneous, light beige fine powder.

Ready to use medium: clear, light blue-green.

Microbiological response after 18-24 hours incubation at 37 °C:

The plates should not be incubated more than 24 hours as the lactose fermenting organisms will mask the non-lactose fermenter.

Storage:

Dehydrated medium should be stored between 10 to 25°C. Once opened, place the container in a dark, dry place. The dehydrated medium should not be used if there is any lump or the colour has changed from the original.