VOGEL-JOHNSON Agar Base

EMD Cat. No. 1.05405.0500
500 g


Medium introducted by ZEBOVITZ et al. (1955) and modified by VOGEL and JOHNSON (1960) for the detection of mannitol-positive staphylococci in clinical specimens and other materials.

This culture medium complies with the recommendations of the United States Pharmakopeia XXIII (1995).


Additives


EMD Cat. No. Product Pack Size
Potassium tellurite trihydrate 100 g



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


Mode of Action
 The growth of accompanying bacteria is almost completely inhibited by tellurite, lithium chloride and a high glycine concentration. The staphylococci may also be slightly inhibited, but this is compensated by the presence of mannitol and glycine. Mannitol also serves as a differentiation reactant as it is degraded to acid by most pathogenic staphylococci; this reaction is indicated by phenol red, which changes its color to yellow. Pathogenic staphylococci also reduce tellurite to metallic tellurium, thus their colonies turn black in color.
Preparation
 Suspend 58 g/liter and let stand for 30 minutes. During dissolving, agitate frequently (aprox. every 5 min). Swirl once more prior to autoclaving. Autoclave (15 min at 121 °C). Prior to use, add 0.24 g potassium tellurite/liter in the form of a filter-sterilized solution at a temperature of about 50 °C, mix. Pour plates.
  •   Do not heat the complete culture medium.
     pH: 7.2 ± 0.2 at 25 °C.
  •   The complete culture medium can be stored in the refrigerator for up to 1 week, whereas the prepared culture medium base can be kept for several months.
    The plates are clear and red.
    Experimental Procedure and Evaluation
     Inoculate the plates massively.
     Incubation: up to 48 hours at 35 °C aerobically.
    Pathogenic staphylococci usually grow within the first 24 hours.
    Appearance of Colonies
         		Microorganisms
    Small, black, sourrounded by yellow zones
         		Staphylococcus aureus
    Small, gray-black, not surrounded by zones
         		Staph. epidermidis, Proteus hauseria (usually completely inhibited) and others


    Quality control

    Test strains
         		Growth /
     Recovery rate %
         		Black colonies
         		color change to yellow
    Staphylococcus aureus ATCC 25923
         		>= 40
         		+
         		+
    Staphylococcus aureus ATCC 6538-P
         		>= 40
         		+
         		+
    Staphylococcus epidermidis ATCC 12228
         		poor / fair
         		±
         		-
    Enterococcus faecalis ATCC 11700
         		none / good
         		±
         		-
    Proteus mirabilis ATCC 29906
         		fair / good
         		+
         		-
    Micrococcus luteus ATCC 10240
         		none / poor

    Escherichia coli ATCC 25922
         		none / poor

    Pseudomonas aeruginosa ATCC 27853
         		none


    Typical Composition (g/liter)
     Peptone from casein 10.0; yeast extract 5.0; di-potassium hydrogen phosphate 5.0; D(-)mannitol 10.0; lithium chloride 5.0; glycine 10.0; phenol red 0.025; agar-agar 13.0.
     Also to be added:
     Potassium tellurite 0.24.
    Literature

    Unted States Pharmacopeia XXIII, Chapter "Microbial Limit Tests" (1995).
     VOGEL, R.A., a. JOHNSON, M.: A modification of the tellurite-glycine medium for the use in the identification of Staphylococcus aureus. - Publ. Hlth. Lab., 18; 131-133 (1960).
     ZEBOVITZ, E., EVANS, J.B., a. NIVEN, C.F.: Tellurite-glycine agar, a selective plating medium for the quantitative detection of coagulase positive staphylococci. - J. Bact., 70; 686-690 (1955).


    Staphylosoccus aureus



    © 2002 Merck KGaA, Darmstadt, Germany