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EMB Agar, Modified is a differential and selective plating medium for the isolation of gram-negative enteric bacilli.

In 1904, Endo developed a culture medium for the isolation of typhoid bacilli from feces,¹ and this medium was widely used in the years immediately following its development. According to Holt-Harris and Teague,² the chief disadvantage of the Endo medium was that the red color of the coliform colonies diffused through the surrounding medium. When larger numbers of these colonies were present on the agar surface, the colorless colonies of the typhoid organisms and other lactose non-fermenters were masked and often overlooked. In 1916, these two scientists reported on the development of a new medium in which the dyes, eosin and methylene blue, were incorporated. Differentiation between lactose fermenters and lactose non-fermenters on this formulation was greatly improved since color diffusion into the agar was eliminated.

The original EMB Agar formulation of Holt-Harris and Teague was modified by Levine who described his medium in a 1918 publication.³ Over the years, it is the Levine Eosin Methylene Blue formulation which has achieved dominant status. The main difference between the two is the inclusion of sucrose in the Holt-Harris and Teague medium. Sucrose is fermented by certain enterics more readily than lactose.

See "Quality Control Procedures."

Quality Control requirements must be performed in accordance with applicable local, state and/or federal regulations or accreditation requirements and your laboratory's standard Quality Control procedures. It is recommended that the user refer to pertinent CLSI (formerly NCCLS) guidance and CLIA regulations for appropriate Quality Control practices.

For in vitro Diagnostic Use.

If excessive moisture is observed, invert the bottom over an off-set lid and allow to air dry in order to prevent formation of a seal between the top and bottom of the plate during incubation.

Pathogenic microorganisms, including hepatitis viruses and Human Immunodeficiency Virus, may be present in clinical specimens. "Standard Precautions"^4-7 and institutional guidelines should be followed in handling all items contaminated with blood and other body fluids. After use, prepared plates, specimen containers and other contaminated materials must be sterilized by autoclaving before discarding.