Prepared Plated Media PPM

EOSIN METHYLENE BLUE AGAR

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Catalog Number : 950

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Description

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EOSIN METHYLENE BLUE AGAR is a diff erential medium similar to Levine EMB Agar (Cat. 1050) and is used for the isolation of Enterobacteria. The use of Eosin Y and Methylene Blue enable diff erentiation between lactose-fermenting and non-fermenting organisms. It is widely used in medical bacteriology, in techniques recommended by APHA and for the detection and enumeration of coliforms, contaminants of foods and drinking water. Peptone provides nitrogen, vitamins, minerals and amino acids essential for growth. Sucrose is added to Lactose as a fermentable carbohydrate to detect coliforms that ferment sucrose more readily than lactose. Eosin Y and Methylene blue dyes are both partial inhibitors of Gram-positive bacteria and pH indicators. Due to the lactose and sucrose, the medium can be diff erential in primary culture: Salmonellae and Shigellae which are lactose-negative can be diff erentiated from other lactose-negative and sucrose-positive organisms such as Proteus vulgaris, Citrobacter and Aeromonas. Dipotassium phosphate acts as a buff er system and Bacteriological agar is the solidifying agent.For the isolation of enteric pathogens from clinical samples, inoculate onto a small area of one quadrant of EMB Agar and streak for isolation, allowing discrete colonies to develop. Incubate at 35 ± 2°C and observe at 24 hours and again at 48 hours. Salmonella and Shigella colonies are translucent and amber colored or colorless. Coliforms that use lactose and/or sucrose produce blue-black colonies with dark centers and a greenish metallic sheen. Other coliforms such as Enterobacter form mucoid, pink colonies. Strains of Enterococcus faecalis are partially inhibited on this medium and appear as colorless colonies. As the medium is moderately inhibitory some staphylococci, streptococci and yeast may grow. Also some Gram-negative non-fermenting bacilli may appear as non lactose fermenters. Further Biochemical tests are necessary for genus identifi cation.