Product number: 7391

MacConkey Agar, CS is used for the isolation and differentiation of Gram-negative enteric bacilli from specimens containing swarming strains of Proteus spp. in a laboratory setting. MacConkey Agar, CS is not intended for use in the diagnosis of disease or other conditions in humans.

MacConkey Agar is based on the bile salt-neutral red-lactose agar of MacConkey. The original MacConkey medium was used to differentiate strains of Salmonella typhosa from members of the coliform group. Formula modifications improved growth of Shigella and Salmonella strains. These modifications include the addition of 0.5% sodium chloride, decreased agar content, altered bile salts, and neutral red concentrations. The formula modifications improved differential reactions between enteric pathogens and coliforms.

MacConkey Agar, CS ("Controlled Swarming") contains carefully selected raw materials to reduce swarming of Proteus spp., which could cause difficulty in isolating and enumerating other Gram-negative bacilli.


Formula Liter
Enzymatic Digest of Gelatin 17 g
Enzymatic Digest of Casein 1.5 g
Enzymatic Digest of Animal Tissue 1.5 g
Lactose 10 g
Bile Salts 1.5 g
Sodium Chloride 5 g
Neutral Red 0.03 g
Crystal Violet 0.001 g
Agar 13.5 g

Final pH: 7.1 ± 0.2 at 25°C
Formula may be adjusted and/or supplemented as required to meet performance specifications.


  1. Suspend 50 g of the medium in one liter of purified water.
  2. Heat with frequent agitation and boil for one minute to completely dissolve the medium.
  3. Autoclave at 121°C for 15 minutes.

Order Details

Product # Product Description
7391A MacConkey Agar, CS, 500 g

Reference Material

7391 - MacConkey Agar, CS, Product Information Sheet [English]

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