MRSA Agar Base is composed of Mueller Hinton Agar and Sodium Chloride. Mueller Hinton Agar is made up of Beef Extract and Acid Hydrolysate of Casein, providing nitrogen, vitamins, carbon, and amino acids. Starch is added to absorb any toxic metabolites produced. Agar is the solidifying agent. The high concentration of Sodium Chloride enhances growth of S. aureus. Oxacillin is added to determine if the particular strain of S. aureus is oxacillin resistant.

Appearance: Homogenous, free-flowing, beige

Prepared Appearance: Prepared medium is hazy and yellow-beige.

Without Oxacillin With Oxacillin S. aureus ATCC 25923 (susceptible) Growth No growth S. aureus ATCC 43300 (resistant) Growth No growth

Inoculate MRSA Agar plates with 10 mcl of a 1:100 dilution of a 0.5 MacFarland standardized suspension of the strain of S. aureus to be tested. Incubate plates for 24 hours at 35°C and examine for any evidence of growth.

The presence of growth indicates oxacillin and methicillin resistance. Lack of growth indicates that the strain lacks the mecA resistance gene.

Important Note: This product as supplied is intended for research use only, not for use in human, therapeutic or diagnostic applications without the expressed written authorization of United States Biological.

1. Suspend 78g of the medium in one liter of purified water. 2. Heat with frequent agitation and boil for one minute to completely dissolve the medium. 3. Autoclave at 121°C for 15 minutes. 4. After cooling to 45-50°C aseptically add 10ml of a filter sterilized solution of oxacillin (6mg /10ml purified water).

Store sealed at 4°C. Protect from moisture and light by keeping container tightly closed.