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Demi-Fraser Broth Base

Demi-Fraser Broth Base is used with ferric ammonium citrate for the selective enrichment of Listeria spp. in a laboratory setting. Demi-Fraser Broth Base is not intended for use in the diagnosis of disease or other conditions in humans.

Listeria monocytogenes, described in 1926 by Murray, Webb, and Swann, is a widespread problem in food industries. Evidence from outbreaks of listeriosis indicate the principle route of transmission is via the consumption of foodstuffs contaminated with Listeria monocytogenes. Implicated vehicles of transmission include turkey frankfurters, coleslaw, pasteurized milk, Mexican style cheese and pate. Listeria spp. are ubiquitous in nature, present in a wide range of unprocessed foods and in soil, sewage, and river waste.

Demi-Fraser Broth Base is a modification of Fraser Broth Base, developed by Fraser and Sperber, and used for the rapid detection of Listeria from food and environmental samples. In Demi-Fraser Broth Base, the nalidixic acid and acriflavine concentration have been reduced in accordance with AFNOR guidelines. Listeria spp. grow over a pH range of 5.0 – 9.6, and can survive in food products with pH levels outside these parameters. Identification of Listeria is based on successful isolation of the organism, biochemical characterization, and serological confirmation.

 

Formula Liter
Enzymatic Digest of Casein 5 g
Enzymatic Digest of Animal Tissue 5 g
Beef Extract 5 g
Yeast Extract 5 g
Sodium Chloride 20 g
Disodium Phosphate *9.6 g
Monopotassium Phosphate 1.35 g
Esculin 1 g
Acriflavin 0.012 g
Nalidixic Acid 0.010 g
Lithium Chloride 3 g

  *Equivalent to 12.0 g of disodium hydrogen phosphate, dihydrate 
Final pH: 7.2 ± 0.2 at 25°C
Formula may be adjusted and/or supplemented as required to meet performance specifications.

Supplement / 5 mL

Fraser Broth 5%, Ferric Ammonium Citrate, 10 mL
filtered sterilized aqueous solution / L

Directions

  1. Dissolve 55 g of the medium in one liter of purified water.
  2. Mix thoroughly.
  3. Autoclave at 121°C for 15 minutes. Cool to room temperature.
  4. Aseptically add 10 mL of Fraser Broth Supplement.

Order Details

Product # Product Description
7656A Demi-Fraser Broth Base, 500 g
7656T Demi-Fraser Broth Base, 5 kg