VRBA- Composition, Principle, Preparation, Results, Uses


Violet Red Bile Agar (VRBA) is a selective and differential medium that is used to isolate and identify coliform bacteria from various sources. Coliform bacteria are Gram-negative, facultatively anaerobic, rod-shaped bacteria that can ferment lactose to produce acid and gas. They are commonly found in the intestinal tract of humans and animals, as well as in soil, water, and food. Coliform bacteria are indicators of fecal contamination and potential pathogens in water and food samples.

VRBA contains ingredients that selectively inhibit the growth of Gram-positive bacteria and other unwanted organisms, while allowing the growth of coliform bacteria. It also contains ingredients that differentiate coliform bacteria from other Gram-negative bacteria based on their ability to ferment lactose. Coliform bacteria produce purple-red colonies with a bile precipitate around them, while non-coliform bacteria produce colorless or pale colonies with no bile precipitate.

VRBA is widely used in microbiology laboratories for the isolation, detection, and enumeration of coliform bacteria in water, milk, dairy products, and clinical samples. It is also used as a confirmatory test for presumptive coliforms obtained from other media, such as MacConkey Agar or Lauryl Sulfate Broth. VRBA can help to identify the presence of Escherichia coli (E. coli), which is the most common and pathogenic member of the coliform group.

In this article, we will discuss the composition, principle, preparation, results, uses, and limitations of VRBA in detail. We will also provide some examples and images of VRBA plates with different types of bacterial growth. We hope that this article will help you to understand the basics and applications of VRBA in microbiology.😊