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Dichloran Rose Bengal Chloramphenicol (DRBC) agar is based on the formulation described by King et al. and is used for the selective isolation and enumeration of yeasts and moulds from food samples. The peptone provides the required carbon, nitrogen and vitamins. Glucose is a fermentable carbohydrate. Potassium di-hydrogen phosphate is a buffering agent and magnesium sulfate is a source of divalent ions and sulfate. In order to curtail the size of the colony diameters of spreading fungi, the antifungal agent dichloran is added to the base and the pH is reduced to 5.6. Rose Bengal suppresses growth of bacteria and restricts the size and height of colonies of more rapidly growing molds. The inclusion of chloramphenicol ensures the suppression of bacteria present in environmental and food samples. Rose Bengal is absorbed by yeast and mold colonies and this further aids in their enumeration. Occasionally reduced recovery of yeasts may be encountered due to the increased activity of Rose Bengal at pH 5.6. -
KM0031 Mannitol Salt Agar is a selective medium for the isolation of Staphylococcus aureus from clinical samples, food, cosmetics and water samples. Chapman showed that adding a higher level of sodium chloride to Mannitol Salt Agar allowed for the recovery of pathogenic staphylococci and inhibits most organisms. Coagulase positive staphylococci (e.g., S. aureus) produce yellow colonies and a surrounding yellow medium while coagulase negative staphylococci produce red colonies and no colour change of the phenol red indicator. The medium conforms to the requirements of the Harmonised EP/USP/JP, is recommended as a primary isolation media by the UK Standards for Microbiology Investigations and tested in accordance with ISO 11133:2014 and Clinical and Laboratory Standards Institute. This medium is also included in the Bacteriological Analytical Manual for cosmetics testing.
