CAT Nº: 1580
Casein Peptone
Meat Peptone
Polisorbate 80
Sodium Chloride
Beef Extract
10.0
Yeast Extract
10.0
Glucose
7.0
5.0
3.0
Lecithin
Sodium Bisulfite
Bacteriological Agar
2.0
1.0
1.0
0.1
15.0
Suspend 54.1 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. Sterilize in autoclave at 121ºC for 15 minutes. Cool to 50ºC, mix well and dispense into plates. The prepared medium should be stored at 2-8°C. The color of the prepared medium is amber, slightly opalescent.
The dehydrated medium should be homogeneous, free-flowing and beige in color. If there are any physical changes, discard the medium.
LETHEEN AGAR MODIFIED is based on the formula described in the FDA Bacteriological Analytical Manual, is a modification of Letheen Broth Base. It is a liquid medium, highly nutritious and recommended for use in the microbiological testing of cosmetics. It can be used to inactivate quarternary ammonium compounds and other preservatives when establishing the number of bacteria present in cosmetics and other materials.
Beef Extract, Casein peptone and Meat peptone provide nitrogen, vitamins, minerals and amino acids essential for growth. Yeast extract is the source of vitamins, particularly of the B-group. Glucose is the fermentable carbohydrate providing carbon and energy. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Lecithin,
Polisorbate 80 and Sodium bisulfite neutralize quaternary ammonium compounds and partially neutralize the preservative system commonly found in cosmetics. Bacteriological Agar is the solidifying agent.
The medium is also used for microbiological samples from surfaces that have been treated with disinfectants.
The following results were obtained in the performance of the medium from type cultures after incubation at a temperature of 35
±
2°C and observed alter 18-24 hours.
Microorganisms
Escherichia coli ATCC 25922
Pseudonornas aeruginas ATCC 27853
Staphy/ococcus aureus ATCC 25923
Staphy/ococcus epidermis ATCC 12228
Salmonella typhimurium ATCC14028
Growth
Good
Good
Good
Good
Good
LABORATORIOS CONDA, S.A.
1

FIJA Bacteriological Analytical Manual (BMA] 1995. Microbiological Methods for cosmetics, Letheen Agar (modified]. Letheen Broth
(modified))
Once opened keep powdered medium closed to avoid hydration.
25ºC
2ºC
LABORATORIOS CONDA, S.A.
2