BAT Agar (Alicyclobacillus Agar)

BAT Medium (Brucella Agar with Teicoplanin)

Highly Selective Medium for Primary Isolation of Brucella Species

Catalog Number: AS-1132

Overview

BAT Medium (Brucella Agar with Teicoplanin) is a highly selective solid culture medium developed for the primary isolation of Brucella species from contaminated clinical, veterinary, and food samples, including milk, tissues, and blood culture material.

This formulation has become the preferred European reference medium, replacing Farrell’s medium in many laboratories due to the superior selectivity and stability provided by teicoplanin. Compared with older antibiotic combinations, teicoplanin offers strong inhibition of contaminating flora while maintaining excellent recovery of Brucella spp.

BAT Medium is referenced in modern protocols aligned with EN ISO 11290-2 modifications, the OIE Terrestrial Manual, and national brucellosis surveillance programs.

Key Features & Benefits

• Highly selective for Brucella species

• Superior suppression of Gram-positive contaminants

• Teicoplanin provides enhanced selectivity with reduced toxicity to target organisms

• Transparent agar base for easy recognition of characteristic colonies

• Preferred alternative to Farrell’s medium in contemporary workflows

Typical Applications

Clinical & Veterinary Microbiology

• Primary isolation of Brucella spp. from blood, bone marrow, and tissue specimens

Food & Dairy Testing

• Isolation of Brucella from milk and dairy products

Reference & Surveillance Laboratories

• Use in national brucellosis control programs

• Confirmation and recovery of Brucella from contaminated samples

Principle of the Medium

The medium is based on Brucella Agar Base, which supplies essential nutrients for the growth of Brucella spp. Selectivity is achieved through the addition of antimicrobial supplements:

• Teicoplanin strongly inhibits Gram-positive background flora

• Polymyxin B suppresses Gram-negative contaminants

• Nalidixic acid (optional) enhances suppression of competing organisms

Sodium bisulfite improves recovery by protecting sensitive organisms. The clear agar base allows characteristic colony morphology to be easily observed during incubation.

Composition (Typical – per litre)

• Brucella Agar Base: 43.0 g
  (casein/meat peptones, yeast extract, glucose, sodium chloride, agar)

• Sodium bisulfite: 0.1 g

Final pH at 25 °C: 7.0 ± 0.2

Supplements

(Added after sterilisation at ~50 °C)

• Teicoplanin: 5 mg/L

• Polymyxin B: 25,000 IU/L (≈5 mg/L)

• Nalidixic acid: 5 mg/L (optional, protocol-dependent)

Preparation (Typical)

• Suspend 43.1 g Brucella Agar Base and 0.1 g sodium bisulfite in 1 L purified water

• Heat to dissolve completely

• Autoclave at 121 °C for 15 minutes

• Cool to 50 °C

• Aseptically add filter-sterilised supplements

• Mix gently and pour into sterile Petri dishes

Typical Colony Appearance

(After 3–7 days incubation at 35–37 °C with 5–10 % CO₂)

• Brucella spp.:
  Small (1–2 mm), smooth, convex, pearly colonies; translucent to opaque; non-haemolytic

Storage & Stability

Prepared plates

• Store at 2–8 °C

• Protect from light

• Use within 4 weeks under recommended conditions

Intended Use & Biosafety

For laboratory research, clinical reference, veterinary, and food microbiology use only.

Brucella species are classified as Risk Group 3 pathogens. All work must be performed by trained personnel in laboratories operating under appropriate BSL-3 containment, in accordance with local regulations.

Not for human or animal therapeutic use.

Quality & Compliance

• Aligned with modern European and OIE reference protocols

• Manufactured under controlled conditions for batch consistency

• Certificate of Analysis (COA) available

• Safety Data Sheet (SDS) available upon request