Letheen Broth is primarily used for assessing the bactericidal activity of quaternary ammonium compounds, and is not intended for use in the diagnosis of disease or other conditions in humans. Letheen Broth is used to determine the phenol coefficient of cationic surfactants as recommended by the Official Methods of Analysis of the Association of Official Analytical Chemists (AOAC). It is also used in hygiene swabbing protocols where it is necessary to neutralise quaternary ammonium compounds. A modification of FDA Broth, Letheen Broth contains lecithin to neutralise quaternary ammonium compounds and Polysorbate 80 to neutralise phenols, hexachlorophene, formalin and (with lecithin) ethanol. Letheen Broth is easily prepared and has a clear appearance aiding in visual inspection for growth. The American Society for Testing Materials (ASTM) specifies the use of Letheen Broth in the Standard Test Method for Preservatives in Water Containing Cosmetics.

• Analyte: non-selective
• Platform: dehydrated culture media
• Formula: peptone 10.0g/L, beef extract 5.0g/L, sodium chloride 5.0g/L, lecithin 0.7g/L, polysorbate 80 5.0g/L
• Grams per litre: 25.70
• Litres per 500g: 19.00