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


Eosin Methylene Blue (EMB) agar is a selective and differential medium that is used for the isolation and differentiation of gram-negative enteric bacteria from clinical and non-clinical specimens. It was initially formulated in 1916 by Holt-Harris and Teague, who used eosin and methylene blue dyes to visibly distinguish between lactose-fermenting and non-lactose-fermenting microorganisms. Later, Levine modified the medium by adding peptone and phosphate, removing sucrose, and increasing the lactose content. This improved the differentiation of fecal and non-fecal types of coliforms.

EMB agar is commonly used in clinical microbiology to detect the presence of specific microbes associated with disease or poor sanitation, such as Escherichia coli, Salmonella, Shigella, and other enteric pathogens. It is also used in testing the quality of water, especially in determining if the water is contaminated by harmful microorganisms.