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Middlebrook 7H11 Agar

Middlebrook 7H11 Agar is used with glycerol and OADC Enrichment for the cultivation of Mycobacterium spp. in a laboratory setting. Middlebrook 7H11 Agar is not intended for use in the diagnosis of disease or other conditions in humans.

There are two types of solid culture media for the primary isolation of mycobacteria, coagulated egg as a base (Lowenstein formulations) and an agar base (Middlebrook formulations). The use of agar-based media for primary isolation of mycobacteria have the following significant advantages:

  1. Agar-based media do not usually liquefy in the presence of contaminating proteolytic organisms.
  2. Agar-based media retain exact concentrations of added drugs because the medium is solidified with agar rather than by inspissation of the egg. There is less drug inactivation when egg ingredients are absent.

Middlebrook 7H11 Agar is a modification of Middlebrook 7H10 Agar Special as recommended by Cohn, Waggoner, and McClately. Cohn et al. added an enzymatic digest of casein and found organism growth was stimulated for fastidious strains of Mycobacterium tuberculosis.

 

Formula Liter
Enzymatic Digest of Casein 1 g
Disodium Phosphate 1.5 g
Monopotassium Phosphate 1.5 g
Ammonium Sulfate 0.5 g
Monosodium Glutamate 0.5 g
Sodium Citrate 0.4 g
Ferric Ammonium Citrate 0.04 g
Magnesium Sulfate 0.05 g
Copper Sulfate 0.001 g
Pyridoxine 0.001 g
Zinc Sulfate 0.001 g
Biotin 0.0005 g
Malachite Green 0.00025 g
Agar 13.5 g

Final pH: 6.6 ± 0.2 at 25°C
Formula may be adjusted and/or supplemented as required to meet performance specifications.

Supplement

Glycerol, 5 mL
OADC Enrichment, 100 mL

Directions

  1. Suspend 19 g of the medium in 900 mL of purified water containing 5 mL of glycerol.
  2. Heat to boiling to dissolve completely.
  3. Autoclave at 121°C for 10 minutes.
  4. Cool to 45 – 50°C and aseptically add 100 mL of OADC Enrichment.

Order Details

Product # Product Description
7244A Middlebrook 7H11 Agar, 500 g
7244T Middlebrook 7H11 Agar, 5 kg