Overview:
BAT Medium (Brucella Agar with Teicoplanin) is a highly selective solid medium specifically developed for the primary isolation of Brucella species (especially B. melitensis, B. abortus, B. suis, and B. ovis) from contaminated clinical, veterinary, and food samples (milk, tissues, blood cultures). It is the current European reference medium (EN ISO 11290-2 modification) and has replaced the older Farrell�s medium in most laboratories because teicoplanin gives superior inhibition of contaminating flora while maintaining excellent Brucella recovery.
Applications:
Primary isolation of Brucella spp. from blood, bone marrow, tissues, milk, and dairy products
Official selective medium in OIE Terrestrial Manual and many national brucellosis programs
Preferred over Farrell�s medium in modern protocols
Key Features:
Extremely effective suppression of Gram-positive contaminants (streptococci, staphylococci, enterococci)
Teicoplanin 5 mg/L is more stable and less toxic to Brucella than bacitracin/polymyxin in Farrell�s
Transparent base ? easy recognition of typical Brucella colonies
Composition (per liter):
Brucella Agar Base (or GC Agar Base) 43.0 g
(contains:
� Casein/meat peptone 10.0 g
� Peptone 10.0 g
� Yeast extract 2.0 g
� Glucose 1.0 g
� NaCl 5.0 g
� Agar 15.0 g)
Sodium bisulfite 0.1 g
Supplements (added after autoclaving, at 50�C):
� Teicoplanin solution 5 mg (final 5 mg/L)
� Polymyxin B 25,000 IU/L (? 5 mg/L)
� Nalidixic acid 5 mg/L (optional in some versions)
Final pH: 7.0 � 0.2 at 25�C
Preparation:
Suspend 43.1 g Brucella Agar Base + 0.1 g sodium bisulfite in 1 L purified water.
Autoclave at 121�C for 15 minutes.
Cool to 50�C.
Aseptically add filter-sterilized teicoplanin (5 mg), polymyxin B (25,000 IU), and nalidixic acid (5 mg) if used.
Mix well and pour plates.
Colony appearance (after 3�7 days at 35�37�C, 5�10 % CO?):
Brucella spp.: 1�2 mm, convex, pearly, translucent to opaque, non-haemolytic.
Storage:
Prepared plates: 2�8�C, protected from light, use within 4 weeks.
For laboratory use only � Brucella is a Risk Group 3 pathogen; work must be performed under BSL-3 conditions.