Chromocult® Enterococci Agar

EMD Cat. No. 1.00950.0100/0500


Selective culture medium for the isolation, differentiation and enumeration of Enterococci in water, foodstuffs and other materials.
 

Ordering information

EMD Cat. No. Product Pack Size
1.00950.0100 Chromocult® Enterococci Agar 100 g
1.00950.0500 Chromocult® Enterococci Agar 500 g

Experimental Procedure and Evaluation Quality Control
Typical Composition (g/liter) Literature
Picture/Image


Mode of Action
 The presence of Enterococci, especially E. faecalis, E. faecium, E. durans and E. hirae, serves as an indicator for faecal contamination.
 Growth of Enterococci is stimulated by selected peptones, phosphates and addition of Tween® 80. Enterococci cleave the unique chromogenic substrates in the medium. This produces red colonies allowing an easy detection of Enterococci.
 Sodium azide and ox bile inhibit most accompanying microbial flora. Non-Enterococci produce colorless, blue/violet or turquoise colonies. These colonies are easily distinguished from the red colored colonies Enterococci produce.
Preparation
 Suspend 33.0 g in 1 liter of purified water by heating in a boiling water bath or in a flowing steam. Stir the contents to assist dissolution (approx. 45 minutes), let the medium cool to 45-50 °C and pour into plates.
  • Do not autoclave! Do not overheat!
     pH. 7.0 ± 0.2 at 25 °C
     The plates are clear and slightly yellow. If stored at +4 ± 2 °C and protected from light the plates are stable for 2 weeks.
    Experimental Procedure
     Inoculate the medium by the pour-plate-method or by spreading the sample material on the surface of the plates. In addition the membrane-filter-technique can also be used.
    The type of membrane filter affects the performance of the medium (growth and coloration of colonies). Best results were obtained using membrane filters of cellulose-mixed-ester material, e.g. Gelman GN-6 (OSSMER, 1999).
     Incubation: 24 ± 4 hours at 35-37 °C.
     If this will neither result in a color change nor in visible growth continue the incubation up to 44 ± 4 hours.
    Evaluation
     Enterococci:
     Red colonies with a diameter of 0.5 to 2 mm
     Non-Enterococci:
     colorless (e.g. Aerococcus viridans ATCC 29503)
     blue/violet (e.g. Aerococcus viridans ATCC 10400)
     turquoise (e.g. Streptococcus equi ATCC 33398)
    Quality control
    Test strains
    		 Inoculum
     (c.f.u./plate)
         		Growth
         		Colony color




    Enterococcus faecalis ATCC 19433
         		30 300
         		good
         		red
    Enterococcus faecium ATCC 882
         		30 300
         		good
         		red
    Enterococcus durans ATCC 6056
         		30 300
         		good
         		red
    Enterococcus hirae ATCC 8043
         		30 300
         		good
         		red
    Aerococcus viridans ATCC 10400
         		1000 - 2000
         		fair / none
         		blue / violet
    Bacillus cereus ATCC 11778
         		1000 - 2000
         		-
         		-
    Escherichia coli ATCC 11775
         		1000 - 2000
         		-
         		-
    Pseudomonas aeruginosa ATCC 27853
         		1000 - 2000
         		-
         		-

    Typical Composition (g/liter)
     Peptones 10.0; sodium chloride 5.0; sodium azide 0.2; di-potassium hydrogenphosphate 3.4; potassium di-hydrogenphosphate 1.6; ox bile 0.5; Tween® 80 1.0; chromogenic-mixture 0.25; agar-agar 11.0
    Literature
    DOTT, H. W., HAVEMEISTER, G., MÜLLER, H. E. and SACRÈ, C. 1982, Faecal streptococci as indicator organisms of drinking water. Zbl. Bakt. Hyg., I. Abt. Orig. A 252; 154-165
     OSSMER, R., SCHMIDT, W., MENDE, U. 1999, Chromocult® Coliform Agar Influence of Membrane Filter Quality on Performance. Posterpresentation Congresso de la Sociedad, Espanola de Microbiologia, Granada, Spain
     AMOROS, I. 1995, Evaluation of Chromocult® Enterococci Broth (with Agar) Posterpresentation Congress of Spanish Society of Microbiology, Madrid
     LITSKY, W., MALLMANN, W. L. and Fifield, C. W. 1953, A new medium for the detection of enterococci in water. Amer. J. Pbl. Hlth. 43; 873-879
     MANAFI, M. and Windhager, K. 1997, Rapid identification of enterococci in water with a new chromogenic assay. Abstr. P-107, pp. 453, Abstracts of the 97 th Meeting of the American Society for Microbiology, Miami, USA
     SNYDER, M. L. and LICHSTEIN, H. C. 1940, Sodium azide as an inhibiting substance for gram-negative bacteria. J. Infect. Dis. 67, 113-115


                                  Chromocult® Enterococci Agar