Thermo Scientific™ Remel™ Modified Lysine Iron Agar

Description

• Selectively isolate Salmonella species using Thermo Scientific™ Remel™ Modified Lysine Iron Agar (Dehydrated)
• Edwards and Fifa developed lysine iron agar (LIA) to detect rapidly fermenting lactose positive Arizona strains 1
• Based on the production of hydrogen sulfide (H 2 S), LIA was modified by Rappold and Bolderdijk by adding novobiocin, bile salts, lactose, and sucrose for selective and differential isolation of Salmonella spp
• 2 and was called Modified Lysine Agar (MLIA)
• It is recommended by the American Public Health Association (APHA) for isolation of Salmonella from food products 3,4
• Modified LIA medium is recommended for use in qualitative procedures for selective isolation of Salmonella spp
• from food samples
• The United States Department of Agriculture (USDA) also observed superior recovery of Salmonella from fresh and cured meat using MLIA as compared to other selective and differential media
• This medium uses lysine as the substrate for detection of the enzyme lysine decarboxylase produced by Salmonella
• Selective medium – Novobiocin inhibits gram-positive organisms such as staphylococci
• Recommended by the American Public Health Association (APHA) to isolate Salmonella from food products 3,4
• Easy to interpret H 2 S Production Positive test – Black precipitate Negative test – No black color development Lysine Decarboxylation Positive test – Purple colonies Negative test – Yellow colonies MLIA has lactose and sucrose as the source of fermentable carbohydrates
• Sodium thiosulfate and ferric ammonium citrate help in the detection of H 2 S-positive Salmonella
• Lysine acts as a substrate for detection of lysine decarboxylase
• Novobiocin is added as the selective agent which inhibits gram-positive organisms such as staphylococci
• When Salmonella spp
• decarboxylate lysine, the amine is converted to cadaverine, which has an alkaline pH, and the medium remains purple
• Salmonella form colonies which are purple with black centers
• Enteric gram-negative bacilli like Proteus spp
• produce H 2 S, but they do not decarboxylate lysine and form yellow colonies
• Citrobacter freundii have been found to mimic salmonellae on this medium.