Technical Data
MRSA Agar Base (Powder)
Microbiological Grade
Storage 4C    Shipping RT

MRSA Agar is used for the determination of methicillin-resistant and oxacillin-resistant Staphylococcus aureus. It was developed to detect the presence of the mecA gene (classic resistance) in S. aureus.

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.

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

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 121C for 15 minutes.

4. After cooling to 45-50C aseptically add 10ml of a filter sterilized solution of oxacillin (6mg /10ml purified water). Storage and Stability:Store sealed at 4C. Protect from moisture and light by keeping container tightly closed.

Test Procedure: Inoculate MRSA Agar plates with 10 mcl of a 1

Results: 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. Murray, P. R., E. J. Baron, and M. A. Pfaller, F. C. Tenover, and R. H. Yolken (eds.). 1995. Manual of clinical microbiology, 6 ed. American Society for Microbiology, Washington, D.C.
2. National Committee for Clinical Laboratory Standards. 1997. Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically. 4th ed. Approved standard M7-A4. National Committee for Clinical Laboratory Standards, Villanova, PA.
3. National Committee for Clinical Laboratory Standards. 1997. Performance standards for antimicrobial disk susceptibility tests. 6th ed. Approved standard M2-A6. National Committee for Clinical Laboratory Standards, Villanova, PA.