Violet Red Bile Dextrose Agar


Cat. No. 1.10275.0500
 (500 g)


Selective agar proposed by MOSSEL et al. (1962, 1963) for the isolation and enumeration of all Enterobacteriaceae species in foodstufs.



This medium complies with the recommendations of the International Organization for Standardization (ISO) (1977) and the German Minister of Health (Bundesminister für das Gesundheitswesen) (1967) and largely conforms with the European Pharmacopeia 6. HECHELMANN et al. (1973) obtained good results with this culture medium. The medium also complies with the German recommendations according § 35 LMBG for food examination.


Click here for information about harmonization of USP/EP chapters on Microbiological Examination of Non-sterile Products (formerly called Microbial Limits Test).

Mode of Action Quality Control
Typical Composition (g/liter) Literature
Preparation


Mode of Action
 Crystal violet and bile salts inhibit the accompanying bacterial flora. Degradation of glucose is accompanied by production of acid, which is indicated by a color change to red and by zones of precipitated bile acids surrounding the colonies. All Enterobacteriaceae are detected as they all degrade glucose to acid. The culture medium is not, however, absolutely specific for these organisms as some other accompanying bacteria (e.g. Aeromonas) also show these reactions.

Typical Composition (g/liter)
 Peptone from gelatin 7.0; yeast extract 3.0; sodium chloride 5.0; D(+)glucose 10.0; bile salt mixture 1.5; neutral red 0.03; crystal violet 0.002; agar-agar 13.0.

Preparation
 Suspend 39.5 g in 1 liter of purified water and heat to boiling with frequent stirring until completely dissolved. Afterwards do not boil more than 2 minutes.
n  Do not autoclave! Do not overheat!
 pH: 7.4 ± 0.2 at 25°C.
 The prepared medium is clear and dark red.
Incubation: for 24 hours at 35°C aerobically.

The identity of suspected Enterobacteriaceae colonies should be confirmed by further tests.

Appearance of Colonies
 		Microorganisms
Red, surrounded by reddish precipitation zones
 		Enterobacteriaceae and others
colorless
 		No Enterobacteriaceae present


Quality control (spiral plating method)




Test strains
 Inoculum (cfu/ml)
 		Recovery rate %
 		Colony color
 		Precipitate
Escherichia coli ATCC 8739
 		10 - 100
 		≥50
 		red
 		+
Salmonella typhimurium ATCC 14028
 		10 - 100
 		≥50
 		red
 		+
Shigella flexneri ATCC 29903
 		10 - 100
 		≥50
 		red
 		+
Yersinia enterocolitica ATCC 9610
 		10 - 100
 		≥50
 		red
 		+
Staphylococcus aureus ATCC 6538
 		≥1 - 104
 		≤0.01

Bacillus cereus ATCC 11778
 		≥1 - 104
 		≤0.01

Pseudomonas aeruginosa ATCC 9027
 		10 - 100
 		≥50
 		Slightly red
Enterococcus faecalis ATCC 19433
 		≥1 - 104
 		≤0.01









Literature

Bundesgesundheitsamt: Amtliche Sammlung von Untersuchungsverfahren nach § 35 LMBG. - Beuth Verlag Berlin, Köln.
Bundesminister für das Gesundheiswesen: "Allgemeine Verwaltungsvorschrift für das Verfahren bei der amtlichen Untersuchung von vorbehandelten Eierprodukten". - Bundesanzeiger, 96; 2-3 (1967) [s. auch Dtsch. Lebensmitt.-Rdsch., 63; 245-249 (1967)].
European Pharmacopeia II, Chapter VIII, 10.
HECHELMANN, H.; ROSSMANITH, E., PERIC, M., u. LEISTNER, L.: Untersuchung zur Ermittlung der Enterobacteriaceae-Zahl bei Schlachtgeflügel. - Fleischwirtsch., 53; 107-113 (1973).
International Organization for Standardization: Meat and meat products - detection and enumeration of Enterobacteriaceae (Reference methods). - Draft International Standard ISO/DIS 5552 (1977).
MOSSEL, D.A.A., MENGERINK, W. HJ., a. SCHOLTS, H.H.A.: Use of a modified MacConkey agar medium for the selective growth and enumeration of all Enterobacteriaceae. - J. Bact., 84; 381 (1962).
MOSSEL, D.A.A., a. CORNELISSEN, A.M.R.: The examination of foods for Enterobacteriaceae using a test of the type generally adopted for the detection of Salmonellae. - J. Appl. Bact., 26; 444-452 (1963).


United States Pharmacopeia 30

<61> Microbiological Examination of Non-sterile Products: Microbial Enumeration Tests (USP 30, page 89).
<62> Microbiological Examination of Non-sterile Products: Tests for Specified Microorganisms (USP 30, page 93).

European Pharmacopeia 6 (Ph. Eur)
2.6.12 Microbiological Harmonization of Non-sterile Products - Microbial Enumeration Test
2.6.12 Microbiological Harmonization of Non-sterile Products - Tests for Specified Microorganisms



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