Middlebrooks 7H10 Selective Medium is an Agar based medium for the isolation of Mycobacteria spp from clinical specimens. It differs from Middlebrooks 7H11 Agar in that it has a lower concentration of Malachite Green, which is said by some workers to make it more suitable for primary isolation.
The medium is complex but includes L-Glutamic Acid, Ammonium Sulphate, Sodium Citrate, Pyridoxine and Biotin as growth factors and Magnesium Sulphate, Ferric Ammonium Citrate as sources of trace ions. Further enrichment is provided by the addition of Oleic Acid, Albumen and Dextrose and it is made selective by the inclusion of Ticarcillin, Polymixin B, Trimethoprim and Amphotericin B.
As with egg media Glycerol is included to enhance the growth of the Mycobacteria and Malachite Green is incorporated to provide a colour contrast between the colonies and the medium as well as contributing some inhibitory effect on organisms other than mycobacteria.
