Eosin Methylene Blue Broth – HX-Media

Principle:- The Eosin Methylene Blue Broth is the combination of Levine and Holt-Harris and Teague formulae. The peptic digest of animal tissue serves as the source of Carbon, Nitrogen, and vitamins, while the two sugars and the dyes Methylene blue and Eosin Y inhibit the Gram positive bacteria. The EMB is a selective media, which differentiate between the lactose fermenters and non-lactose fermenters; some gram negative bacteria sometimes do not utilize the lactose or are very slow at lactose utilizing hence the sucrose is used as secondary carbohydrate source. The lactose non-fermenters such as Salmonella sp. raise the pH of surrounding by deamination of protein thus resulting in change of pH, solubilize the Eosin Methyl red complex and grow as colorless colonies. While the coliforms produce black purple colonies, such as Escherichia coli forms characteristic green colored metallic sheen. The major limitation of this medium is presence of Greenish metallic Sheen is not confirmatory for all strains of E coli as some strains may grow without developing the green metallic sheen.

Use:- Recommended for the differential isolation of the gram negative Enteric Bacilli from clinical and non-clinical samples.