Mueller-Hinton Agar is a defined medium used primarily in Antimicrobial Sensitivity Testing using the disc diffusion technique described by Bauer-Kirby. It is approved as the definitive medium for this purpose by the National Committee for Clinical Laboratory Standards (NCCLS) in USA. It is low in Tetracycline antagonists and although the majority of organisms will grow on the medium without the need for additional supplementation this particular formulation has been enriched with Defibrinated Sheep Blood (5%) making it suitable for use with the more fastidious organisms including many of those that are dependant on Thymine and Thymidine for their growth. The medium can also be used for the isolation of Neisseria spp.
NB: In view of the possible effect on the pH of the medium when used with organisms requiring incubation in a CO2 enriched environment it is essential to include control organisms with the test plates.