Brucella Medium Base

Beef extract and peptone provide nitrogen, vitamins, minerals and amino acids essential for growth. Glucose is the fermentable carbohydrate providing carbon and energy. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Bacteriological agar is the solidifying agent. The addition of the supplement enhances the medium's selectivity for the growth of Brucella.

Brucella species are level 3 pathogens and cause brucellosis, a zoonotic disease. It is usually transmitted through milk, dairy products, meat and direct contact with infected animals.

It is widely used for the isolation of Brucella in food materials and dairy products.

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

Preparation

Suspend 45 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 121 °C for 15 minutes. Cool to 45-50 °C and add 5% horse serum, inactivated by heating at 56 °C for 80 minutes. To obtain a selective medium, add 2 vials of Brucella Selective Supplement (LC-6060). Homogenize gently and pour into Petri dishes.

Streak plate method

1. In a Petri dish, add 12-15 mL of molten agar and let it solidify.
2. Inoculate 10 µL of the initial suspension and/or diluted sample.
3. Extend the inoculum with a sterile loop on the agar surface.
4. Incubate the plates in an inverted position at a temperature of 35 ± 2 °C in an atmosphere of 5-10% CO₂ and observe after 72 hours.

The microbiological test should be carried out by the end-user laboratory.

• Kuzdas and Morse, J. Bact. 66:502. 1953.
• Rennoux G. Ann. Inst. Pasteur, 87:325. 1954.
• Standard Methods for the Examination of Dairy Products. 10th Ed. APHA, Inc. New York, 1960.
• Smith Louis Ds. The Pathogenic Anaerobic Bacteria. C. Thomas Pub. Springfield, Il, 1975.