Mueller Hinton Agar II is used in antimicrobial susceptibility testing by the disk diffusion method. This formula conforms to Clinical and Laboratory Standard Institute (CLSI), formerly National Committee for Clinical Laboratory Standards (NCCLS).
Mueller Hinton Agar II is based on the formula recommended by Mueller and Hinton for the primary isolation of Neisseria species. Mueller and Hinton selected pea meal extract agar as a simple transparent medium containing heat stable ingredients. During their modification, starch replaced the growth-promoting properties of pea extract, acting as a “protective colloid” against toxic substances.
Bauer, Kirby, Sherris and Tuck recommended Mueller Hinton Agar for performing antibiotic susceptibility tests using a single disk of high concentration. This un-supplemented medium has been selected by the Clinical and Laboratory Standard Institute (CLSI) for several reasons. This medium is low in sulfonamide, trimethoprim and tetracycline inhibitors, and provides satisfactory growth of most non-fastidious pathogens along with demonstrating batch-to-batch reproducibility.
Mueller Hinton Agar is often abbreviated as M-H Agar and complies with requirements of the World Health Organization. Mueller Hinton Agar is specified in FDA Bacteriological Analytical Manual for food testing, and procedures commonly performed on aerobic and facultatively anaerobic bacteria. A variety of supplements can be added to Mueller Hinton Agar, including 5% defibrinated sheep or horse blood, 1% growth supplement and 2% sodium chloride.
