Kanamycin Esculin Azide Agar

EMD Cat. No. 1.05222.0500
500 g


For the isolation, differentiation and enumeration of enterococci in foodstuffs, water and other materials according to MOSSEL et al. (1978).

Kanamycin esculin azide agar is, unlike culture media containing bile which sometimes exhibit a fluctuating selectivity towards D-streptococci, always highly selective for this group of bacteria.






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


Mode of Action
 Kanamycin and azide largely inhibit the accompanying bacterial flora. D-streptococci are, however, only slightly sensitive to these substances, so they can grow almost normal and hydrolyse the glucoside esculin to give glucose and esculetin. Esculetin forms an olive green to black complex with iron(III) ions.
Preparation
 Suspend 47.5 g/liter, autoclave (15 min at 121 °C), and pour plates.
  •   Do not overheat.
     pH: 7.1 ± 0.2 at 25 °C.
     The plates are clear and brown-bluish.
    Experimental Procedure and Evaluation
     Inoculate by spreading the samples on the surface of the plates.
     Incubation: up to 3 days at 35 °C or 42 °C aerobically. The higher temperature increases the selectivity of the medium.
    Enterococci colonies are surrounded by a dark zone. Confirmatory tests, e.g. catalase test, glucose utilisation and growth at 45 °C ± 1 °C, may be carried out.
    Quality control (spiral plating method)

    Test strains
    		 Inoculum
     (cfu/ml)
         		Recovery rate (%)
         		color change to olivegreen-black
    Enterococcus faecalis ATCC 11700
         		10³-105
         		>= 70
         		+
    Enterococcus hirae ATCC 8043 8043
         		10³-105
         		>= 70
         		+
    Enterococcus durans BFM* 11507
         		10³-105
         		>= 70
         		+
    Staphylococcus aureus ATCC 6538-P
         		10³-105
         		Not limited
         		-
    Bacillus cereus ATCC 11778
         		> 105
         		<= 0.01
         		-
    Escherichia coli ATCC 11775
         		> 105
         		<= 0.01
         		-

    * Bundesanstalt f. Milchforschung, Kiel, Germany
    Typical Composition (g/liter)
     Peptones from casein 20.0; yeast extract 5.0; sodium chloride 5.0; sodium citrate 1.0; sodium azide 0.15; kanamycin sulfate 002; esculin 1.0; ammonium iron(III) citrate 0.5; agar-agar 15.0.
    Literature

    BRANDL, E., ASPERGER, H., PFLEGER, F., u. IBEN, CH.: Zum Vorkommen von D-Streptokokken in Käse. - Arch. Lebensmittelhyg., 36; 18-22 (1985).
     MOSSEL, D.A.A., BIJKER, P.G.H., a. EELDERING, J.: Streptokokken der Lancefield-Gruppe D in Lebensmitteln und Trinkwasser - Ihre Bedeutung, Erfassung und Bekämpfung. - Arch. f. Lebensmittelhyg., 29; 121-127 (1978).


    Enterococcus faecalis



    © 2002 Merck KGaA, Darmstadt, Germany