CRITERION™ VIOLET RED BILE Agar WITH MUG

Cat. no. C7250 CRITERION™ Violet Red Bile Agar with MUG 83.2gm
Cat. no. C7251 CRITERION™ Violet Red Bile Agar with MUG 500gm
Cat. no. C7252 CRITERION™ Violet Red Bile Agar with MUG 2kg
Cat. no. C7253 CRITERION™ Violet Red Bile Agar with MUG 10kg
Cat. no. C7254 CRITERION™ Violet Red Bile Agar with MUG 50kg

INTENDED USE

Hardy Diagnostics CRITERION™ Violet Red Bile Agar with MUG is recommended for the detection of Escherichia coli and total coliforms in food and dairy products.

This dehydrated culture medium is a raw material intended to be used in the making of prepared media products, which will require further processing, additional ingredients, or supplements.

SUMMARY(1-3)

Violet Red Bile Agar is a selective medium used to detect and enumerate lactose-fermenting coliform microorganisms. This media is specified as a standard methods procedure for use in the microbiological analysis of milk and other dairy products. Lactose-fermenting microorganisms produce pink to red colonies that are generally surrounded by a reddish zone of precipitated bile. Non-lactose-fermenting microorganisms result in colorless colonies.

The addition of 4-methylumbelliferyl-beta-D-glucuronide (MUG) allows presumptive identification of Escherichia coli from the primary plating medium. Most strains of E. coli (96-97%) produce glucuronidase, an enzyme that hydrolyzes MUG to 4-methylumbelliferone. This compound fluoresces under long-wave ultraviolet light (366nm). The addition of MUG to this formulation allows colonies of beta-glucuronidase positive strains of E. coli to exhibit blue fluorescent halos when examined under long-wave UV light.

The medium contains bile salts and crystal violet which serve as inhibitory agents toward some gram-positive microorganisms, especially staphylococci. Neutral red is employed as the pH indicator. The peptone serves as a source of carbon, nitrogen, vitamins and minerals. Lactose is also used as a carbohydrate source, while yeast extract provides B vitamins which enhance bacterial growth. Agar is used for solidification.

FORMULA*

Gram weight per liter: 41.6gm/L
Lactose 10.0gm
Gelatin Peptone 7.0gm
Sodium Chloride 5.0gm
Yeast Extract 3.0gm
Bile Salts No. 3 1.5gm
MUG (4-methylumbelliferyl-beta-D-glucuronide) 0.1gm
Neutral Red 0.03gm
Crystal Violet 0.002gm
Agar 15.0gm

Final pH 7.4 +/- 0.2 at 25ºC.

* Adjusted and/or supplemented as required to meet performance criteria.

STORAGE AND SHELF LIFE

Store the sealed bottle(s) containing dehydrated culture medium at 2-30ºC. Dehydrated culture medium is very hygroscopic. Keep lid tightly sealed. Protect dehydrated culture media from moisture and light. The dehydrated culture media should be discarded if it is not free-flowing or if the color has changed from its original reddish-beige.

Store the prepared culture media at 2-8ºC.

PRECAUTIONS

METHOD OF PREPARATION FOR DEHYDRATED CULTURE MEDIA

1. Suspend 41.6gm of the dehydrated culture media in 1 liter of distilled or deionized water. Stir to mix thoroughly.

2. Heat to boiling to dissolve completely. Do not boil for more than two minutes.

3. Do not autoclave.

4. Cool to 45-50ºC. and aseptically pour plates.

PROCEDURE AND INTERPRETATION OF RESULTS

For information on procedures and interpretation of results, consult listed references.

LIMITATIONS(1-5)

Strains of glucuronidase-negative E.coli have been reported as well as glucuronidase-positive strains that do not fluoresce.

If a Salmonella or Shigella strain is encountered that fluoresces and exhibits colorless growth, differentiate from E. coli using other parameters such as gas production, lactose fermentation, growth at 44.5 degrees C. or further biochemical and/or serological tests.

MATERIALS REQUIRED BUT NOT PROVIDED

Standard microbiological supplies and equipment such as UV lamps, autoclaves, incinerators, petri dishes, loops, and incubators, etc., are not provided.

QUALITY CONTROL

Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Escherichia coli
ATCC ® 25922
A 22-26hr 35°C Aerobic Growth; pink-red colonies, red precipitate around colonies and fluoresce (+) under UV light
Salmonella enterica
ATCC ® 14028
A 22-26hr 35°C Aerobic Growth; colorless colonies, fluoresce
(-) under UV light
Enterococcus faecalis
ATCC ® 29212
B 22-26hr 35°C Aerobic Partial to complete inhibition

User Quality Control

Physical Appearance

CRITERION™ Violet Red Bile Agar with MUG powder should appear homogeneous, free-flowing, and reddish-beige in color. The prepared media should appear clear to slightly opalescent, and reddish-purple in color.

REFERENCES

1. American Public Health Association. Standard Methods for the Examination of Dairy Products, APHA, Washington, D.C.

2. APHA Technical Committee on Microbiological Methods for Foods. Compendium of Methods for the Microbiological Examination of Foods, APHA, Washington, D.C.

3. American Public Health Association. Standard Methods for the Examination of Water and Wastewater, APHA, Washington, D.C.

4. U.S. Food and Drug Administration. Bacteriological Analytical Manual. AOAC, Arlington, VA.
http://www.fda.gov/Food/FoodScienceResearch/LaboratoryMethods/ucm2006949.htm.


ATCC is a registered trademark of the American Type Culture Collection.

062716gr