Letheen Broth Base, Modified

Letheen Broth Base, Modified is used with Polysorbate 80 for the recovery of microorganisms from cosmetics in a laboratory setting. Letheen Broth Base, Modified is not intended for use in the diagnosis of disease or other conditions in humans.

In 1948, Weber and Black described the value of a highly nutritional solid medium containing neutralizing agents for quaternary ammonium compounds in sanitizers. The addition of Lecithin and Polysorbate 80 to Tryptone Glucose Extract (TGE) Agar resulted in a medium that effectively neutralizes quaternary ammonium compounds in testing of germicidal activity. Total neutralization of disinfectants is critical. Disinfectant residues can result in a false negative (no-growth) test.

Letheen Broth Base, Modified is based on the formula described in FDA Bacteriological Analytical Manual, and a modification of Letheen Broth Base. Letheen Broth Base, Modified is recommended by the FDA for use in the microbiological testing of cosmetics.


Formula Liter
Letheen Broth Base 20.7 g
Enzymatic Digest of Casein 5 g
Enzymatic Digest of Animal Tissue 10 g
Yeast Extract 2 g
Sodium Bisulfite 0.1 g

Final pH: 7.2 ± 0.2 at 25°C
Formula may be adjusted and/or supplemented as required to meet performance specifications.

Supplement / Liter

Tween 80 (Polysorbate 80), 5 g


  1. Dissolve 37.8 g of the medium and 5 g of Tween 80 (Polysorbate 80) (#7992) in one liter of purified water.
  2. Heat with frequent agitation to completely dissolve the medium.
  3. Autoclave at 121°C for 15 minutes.

Order Details

Product # Product Description
7496A Letheen Broth Base, Modified, 500 g
7496T Letheen Broth Base, Modified, 5 kg