Middlebrook 7H11 Agar Base media is used for the isolation, cultivation, and sensitivity testing of Mycobacterium species. This agar base contains many inorganic salts which help the growth of Mycobacteria. Citric acid formed from sodium citrate helps in retaining inorganic cations in solution. Glycerol supplies carbon and energy. The Middlebrook OADC Supplement (M0678) contains oleic acid, bovine albumin, sodium chloride, dextrose and catalase. Oleic acid and other long chain fatty acids are essential for the metabolism of Mycobacteria. Dextrose is an energy source. Catalase neutralizes toxic peroxides. Albumin protects tubercle bacilli from toxic agents. Malachite green partially inhibits other bacteria.

There are two types of solid culture media for the primary isolation of Mycobacteria. Egg-based (Lowenstein’s formulation) and agar-based (Middlebrook formulation)
The latter has the following advantages over the egg-based media

The Middlebrook 7H11 agar base does not liquify easily in the presence of contaminating proteolytic organisms

There is less inactivation of added drugs when egg ingredients are absent

Ingredients (g/L)
Casein enzymatic hydrolysate, 1.00
Ammonium sulfate, 0.50
Monopotassium phosphate, 1.50
Disodium phosphate, 1.50
Sodium citrate, 0.40
Magnesium sulfate, 0.05
L-Glutamic acid, 0.50
Ferric ammonium citrate, 0.04
Pyridoxine, 0.001
Biotin, 0.0005
Malachite green, 0.001
Agar, 15.00

Suspend 10.25 g of Middlebrook 7H11 Agar Base in 450 ml of distilled water. Add 2.5 ml of glycerol (Cat. No. 49767). Boil to dissolve the medium completely. Sterilize by autoclaving at 15 lbs. pressure (121°C) for 15 minutes. Cool to 50°C and aseptically add 1 vial Middlebrook OADC Growth Supplement (M0678). Mix thoroughly before dispensing.

GRANUCULT is a registered trademark of Merck KGaA, Darmstadt, Germany

NutriSelect is a registered trademark of Merck KGaA, Darmstadt, Germany

We offer two media types: the superior granulated GranuCult^® and the cost-efficient powdered NutriSelect^® culture media, depending on your needs. The designations basic, plus, or prime are added to indicate the quality control level, from basic quality control to standard QC plus to prime for full regulatory compliance.