Product number: 7405

Selective Strep Agar, Modified No. 2 is used with blood for the selective isolation of group A streptococci in a laboratory setting. Selective Strep Agar, Modified No. 2 is not intended for use in the diagnosis of disease or other conditions in humans.

Selective Streptococcus Agar was developed by Roantree et al., for the isolation of group A beta-hemolytic streptococci. Further improvement was made by adding yeast nucleic acid and maltose, promoting increased colony size and enhanced clarity of hemolytic zones produced by group A streptococci. This modified formula also increased inhibition of Staphylococcus spp.


Formula Liter
Enzymatic Digest of Casein 10 g
Beef Extract 6.7 g
Maltose 0.25 g
Nucleic Acid 6 g
Sodium Chloride 5 g
Neomycin Sulfate 0.002 g
Polymyxin B Sulfate 0.024 g
Selective Agents 0.00289 g
Agar 15 g

Final pH: 7.3 ± 0.2 at 25°C
Formula may be adjusted and/or supplemented as required to meet performance specifications.


  1. Suspend 43 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. Do not overheat.
  4. Prepare 5 – 10% blood agar by aseptically adding the appropriate volume of sterile defibrinated blood to melted sterile agar medium, cooled to 45 – 50°C.

Order Details

Product # Product Description
7405A Selective Streptococcus Agar, Modified No. 2, 500 g

Reference Material

7405 - Selective Strep Agar, Modified No. 2, Product Information Sheet [English]

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