Brucella Agar- Composition, Principle, Preparation, Results, Uses


Brucella Agar is a type of culture medium that is used for the isolation and cultivation of Brucella spp. and other fastidious microorganisms. Brucella spp. are gram-negative, facultative intracellular bacteria that cause brucellosis, a zoonotic disease that affects humans and animals. Brucella Agar was developed by Brewer in 1940 as a modification of the serum dextrose agar used by Huddleson.

The composition of Brucella Agar is as follows:

  • Peptones: 10 g/L
  • Yeast extract: 2 g/L
  • Dextrose: 1 g/L
  • Sodium chloride: 5 g/L
  • Sodium bisulfite: 0.1 g/L
  • Agar: 15 g/L

The peptones provide organic nitrogen and amino acids for the growth of microorganisms. The yeast extract is a source of B-complex vitamins and other growth factors. The dextrose serves as an energy source. The sodium bisulfite acts as a reducing agent to create a low-oxygen environment. The sodium chloride maintains the osmotic balance of the medium. The agar is the solidifying agent that allows the formation of discrete colonies.

Brucella Agar has a final pH of 7.0 ± 0.2 at 25°C, which is suitable for the growth of most bacteria. It is a non-selective and non-differential medium, meaning that it does not inhibit or differentiate between different types of bacteria. However, it can be supplemented with blood, antibiotics, or other additives to enhance its performance for specific purposes.

Brucella Agar is widely used in clinical and veterinary microbiology, as well as in food and environmental testing. It is especially useful for the isolation of Brucella spp., which are highly fastidious and require special growth conditions. Brucella Agar can also support the growth of other bacteria, such as Streptococcus pneumoniae, Streptococcus viridans, Neisseria meningitidis, and Campylobacter spp.