Crome Agar MRSA

CROME Agar MRSA is a selective and differential medium for the qualitative direct detection methicillin resistant Staphylococcus aureus (MRSA) in clinical settings. The test is performed on anterior nares swab specimens from patients and healthcare workers to screen for MRSA colonization. MRSA are a major cause of nosocomial and life threatening infections and have been associated with a significantly higher morbidity1.

CROME Agar MRSA medium permits the direct detection and identification of MRSA through the incorporation of specific chromogenic substrates and cefoxitin. MRSA strains will grow in the presence of cefoxitin and produce mauve-colored colonies due to hydrolysis of the chromogenic substrate2. Additional selective agents are incorporated for the suppression of gram-negative organisms, yeast and some gram-positive cocci. Bacteria other than MRSA may utilize other chromogenic substrates in the medium resulting in blue to blue/green colored colonies or if no chromogenic substrates are utilized, the colonies appear as white or colorless.

Product NameCatalog #Quantity
Crome Agar MRSA mono plate, 90 x 15 mm CC9240P 10/pk

Quality Control

The following organisms are routinely used for testing for this medium.
Test OrganismsResults
aStaphylococcus aureus ATCC® 25923 No Growth
aStaphylococcus aureus ATCC® 43300 Growth with mauve colonies

User Quality Control

Check for signs of contamination and deterioration. Users of commercially prepared media may be required to perform quality control testing with at least one known organism to demonstrate growth or a positive reaction; and at least one organism to demonstrate inhibition or a negative reaction (where applicable).

Ingredients g/L

(Final pH 7.2 +/- 0.2 at 25°C)
Chromopeptone 40.0
Sodium Chloride 25.0
Cefoxitin 0.006
Chromogen Mix 0.50
Inhibitory Agents 0.07
Agar 14.0
2 total citations

  1. Muto, C. A., J. A. Jernigan, B. E. Ostrowosky, H. M. Richet, W. R. Jarvis, J. M. Boyce, B. M. Farr. 2003. SHEA guideline for preventing nosocomial transmission of multidrug-resistant strains of Staphylococcus aureus and Enterococcus. Infect. Control and Hospital Epidemiol. May 362-386.
  2. Clinical and Laboratory Standards Institute. 2008. Performance standards for antimicrobial susceptibility testing; Eighteenth Informational Supplement, M100-S18. CLSI, Wayne, PA.
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