Letheen Broth Modified ISO/BAM

This medium is also recommended by the ISO 21149, ISO 21150, ISO 18415, ISO 22718, ISO 22717 and ISO 18416 standards for the enrichment of aerobic bacteria, yeast and molds in cosmetic products.

Beef extract and casein peptone provide nitrogen, vitamins, minerals and amino acids essential for growth. Yeast extract is the source of vitamins, particularly of the B-group. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Lecithin, polysorbate 80 and sodium bisulfite neutralize quaternary ammonium compounds and partially neutralize the preservative system commonly found in cosmetics.

The medium is also used for microbiological samples from surfaces that have been treated with disinfectants.

Typical formula in g/L, adjusted and/or supplemented as required to meet performance criteria.

Preparation

Suspend 42.8 grams of the medium in one liter of distilled water. Mix well and dissolve by heating with frequent agitation. Boil for one minute until complete dissolution. Dispense into appropriate containers and sterilize at 121 °C for 15 minutes.

Instructions for use

For the enrichment of aerobic bacteria present in cosmetic products:

1. Prepare the initial suspension and disperse in the broth.
2. Incubate at 35 ± 2 °C for 18-24 hours.
3. Subculture a defined amount of the above solution onto appropriate media depending on the microorganism to be detected: MacConkey Agar (LC-1052) for E. coli, Baird Parker Agar (LC-1100) for S. aureus, Cetrimide Agar (LC-1102) for P. aeruginosa and Sabouraud Dextrose Agar + Chloramphenicol for C. albicans.

• FDA Bacteriological Analytical Manual (BAM) 1995. Microbiological Methods for cosmetics, Letheen Agar (modified), Letheen Broth (modified).