Mannitol Salt Agar

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.

Additional Information

Shelf Life (days)

Storage Temp (°C)

Dehydrated Medium Appearance

Prepared Medium Appearance

Dehydrated Medium Colour

Prepared Medium Colour

Dehydrated pH

Prepared pH

Product Description

According to CLSI:

Organisms Ref. No Result
Staphylococcus aureus NCTC 10788 Growth: Yellow colonies with yellow halo
Staphylococcus aureus NCTC 12981 Growth: Yellow colonies with yellow halo
Staphylococcus epidermidis NCTC 13360 Growth: Pale pink colonies with no halo
Proteus mirabilis NCTC 10975 Inhibited

 

According to the Harmonised EP/USP/JP:

Organisms Ref. No Result
Staphylococcus aureus NCTC 10788 Growth: Yellow colonies with yellow halo
Staphylococcus epidermidis NCTC 13360 Growth: Pale pink colonies with no halo
Escherichia coli NCTC 10975 Inhibited

Formula*

g/L
Pancreatic digest of casein 5.0
Peptic digest of animal tissue 5.0
Beef extract 1.0
Sodium chloride 75.0
Mannitol 10.0
Phenol red 0.025
Agar 15.0
Total 111.0
*Adjusted/supplemented as required to meet performance requirements

Preparation

Suspend 111g of the medium in one litre of deionised / purified water. Allow the medium to soak whilst mixing for 10 minutes. Heat with frequent agitation and boil for one minute to completely dissolve the medium. Sterilise at 121°C for 15 minutes. Cool to 45-50°C and aseptically dispense into appropriate sterile containers.