m-Enterococcus Agar

EMD Cat. No. 1.05262.0500
500 g


For the enumeration of enterococci in water and other liquids by the membrane filtration technique according to SLANETZ und BARTLEY (1957).



Additives





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


Mode of Action
 The growth of the entire accompanying Gram-negative microbial flora is inhibited by sodium azide. Enterococci reduce TTC to give a red formazan, their colonies are thus red in color. According to LACHICA and HARTMAN (1968), the selectivity for enterococci can be improved by adding carbonate and Tween 80®.

Preparation
 Suspend 41.5 g/liter, sterilize by heating for 20 minutes in a current of steam (e.g. autoclave without excess pressure). Afterwards cool rapidly!
  •   Do not autoclave.
     When using Cat. No. 1.05289.0500, add 10 ml of a filtersterilized 1 % 2,3,5-triphenyltetrazolium chloride solution/liter to the base medium at a temperature of approximately 50 °C. Pour plates.
     pH: 7.2 ± 0.2 at 25 °C.
     The plates are clear and yellowish-brown. A reddish color with Cat. No. 1.05262.500 might occur.

    Experimental Procedure and Evaluation
     Place the inoculated membrane filters on the surface of the plates.
     Incubation: up to 48 hours at 35 °C aerobically.

    Pink to brown colonies with a diameter of 0.5 to 2 mm are usually enterococci.

    Quality control

    Test strains
    		 Growth
         		Red colonies
    Streptococcus pyogenes ATCC 12344
         		poor / fair
         		-
    Streptococcus agalactiae ATCC 13813
         		none / poor
         		-
    Enterococcus faecalis ATCC 11700
         		good / very good
         		+
    Enterococcus faecalis ATCC 19433
         		good / very good
         		+
    Enterococcus hirae ATCC 8043
         		good / very good
         		+ (poor)
    Staphylococcus aureus ATCC 25923
         		none
    Escherichia coli ATCC 25922
         		none
    Pseudomonas aeruginosa ATCC 27853
         		none

    Typical Composition (g/liter)
     Peptone from casein 15.0; peptone from soymeal 5.0; yeast extract 5.0; D(+)glucose 2.0; di-potassium hydrogen phosphate 4.0; sodium azide 0.4; 2,3,5-triphenyltetrazolium chloride (not present in Cat. No. 1.05289.0500) 0.1; agar-agar 10.0.
    Literature

    LACHICA, R.V.F., a. HARTMAN, P.A.: Two improved media for isolating and enumerating enterococci in certain frozen foods. J. Appl. Bact., 31; 151-156 (1968).
     SLANETZ, L.W., a. BARTLEY, C.H.: Numbers of enterococci in water, sewage, and faeces determined by the membrane filter technique with an improved medium J. Bact., 74; 591-595 (1957).


    Enterococcus faecalis



    © 2002 Merck KGaA, Darmstadt, Germany