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GC Agar

GC Agar is used with hemoglobin and enrichment for the isolation and cultivation of Neisseria gonorrhoeae and other fastidious organisms in a laboratory setting. GC Agar is not intended for use in the diagnosis of disease or other conditions in humans.

In 1945, Johnston described a medium that grew N. gonorrhoeae in 24 rather than 48 hours. GC Agar was introduced in 1947 with reduced agar content. While investigating the growth rate of gonococcus, a medium containing growth factors glutamine and cocarboxylase improved recovery. In 1964, Thayer and Martin formulated a medium incorporating the antibiotics Polymyxin B and Ristocetin, with added supplements, into GC Agar. Thayer and Martin improved their medium by replacing the antibiotics with a new solution of Colistin, Vancomycin, and Nystatin (CVN). In 1970, Martin and Lester improved the new Thayer-Martin Medium by increasing the agar and glucose, and adding Trimethoprim Lactate (T), calling it Modified Thayer-Martin (MTM) Medium. Martin and Lewis improved selectivity of MTM by increasing the concentration of Vancomycin and replacing Nystatin with Anisomycin for greater inhibition of yeasts, known as Martin Lewis (ML) Agar.

 

Formula Liter
Enzymatic Digest of Casein 7.5 g
Enzymatic Digest of Animal Tissue 7.5 g
Corn Starch 1 g
Dipotassium Phosphate 4 g
Monopotassium Phosphate 1 g
Sodium Chloride 5 g
Agar 10 g

Final pH: 7.2 ± 0.2 at 25°C
Formula may be adjusted and/or supplemented as required to meet performance specifications.

Supplements

Hemoglobin Solution, 2%, 100 mL
Growth Enrichment, 2 mL
Antimicrobials, if required

Directions

  1. Suspend 7.2 g of the medium in 100 mL 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. Cool to 45 – 50°C.
  4. Prepare 100 mL of a 2% hemoglobin solution and autoclave at 121°C for 15 minutes.
  5. Cool to 45 – 50°C and aseptically add to the molten GC Agar.
  6. Add 2 mL of growth enrichment. Add antimicrobials, if desired. Mix thoroughly and dispense.

Order Details

Product # Product Description
7104A GC Agar, 500 g
7104T GC Agar, 5 kg