Eosin Methylene Blue (EMB) Agar Levine

Eosin Methylene Blue Agar Levine is used for the isolation and differentiation of Gram-negative enteric bacilli and is not intended for use in the diagnosis of disease or other conditions in humans.

This medium was introduced in 1916 by Holt-Harris and Teague to differentiate Escherichia spp. and Aerobacter spp. It was modified by Levine in 1918 who removed sucrose from the formula and increased the lactose content. The distinctive metallic sheen produced by E. coli on this medium is due to acid production resulting in an amide bonding between the eosin and methylene blue, other coliforms do not produce enough acid to cause this reaction. Eosin inhibits most Gram-positive organisms. The prepared medium is sensitive to light.