CRITERION™ LETHEEN BROTH

Cat. no. C6020 CRITERION™ Letheen Broth 51.4gm
Cat. no. C6021 CRITERION™ Letheen Broth 500gm
Cat. no. C6022 CRITERION™ Letheen Broth 2kg
Cat. no. C6023 CRITERION™ Letheen Broth 10kg
Cat. no. C6024 CRITERION™ Letheen Broth 50kg

INTENDED USE

Hardy Diagnostics CRITERION™ Letheen Broth is used to determine the antimicrobial activity of quaternary ammonium compounds.

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

Quaternary ammonium compounds are molecules which contain a nitrogen atom with four other atoms bonded to it. Most quaternary ammonium compounds are organic compounds and have biological activity. These compounds often work well as disinfectants, offering bactericidal and bacteriostatic effects. Letheen Broth is used in the AOAC procedure for determining the effect of these bactericidal compounds.(1)

Letheen media is formulated according to the guidelines set by the AOAC for the determination of phenol coefficient of quaternary ammonium compounds.(1) The medium contains beef extract and peptic digest of animal tissue to provide a nutrient rich medium supporting the growth of a variety of microorganisms. Quaternary ammonia compounds are neutralized by lecithin while phenolic disinfectants and hexachlorophene are neutralized by Tween® 80. Together, lecithin and Tween® 80 neutralize ethanol.(1)

FORMULA

Gram weight per liter: 25.7gm/L
Peptic Digest of Animal Tissue 10.0gm
Beef Extract 5.0gm
Sodium Chloride 5.0gm
Tween®80 5.0gm
Lecithin 0.7gm

Final pH 7.0 +/- 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 2-8ºC. 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 homogeneous, moist, and lumpy or if the color has changed from its original beige.

Store the prepared culture media at 2-8ºC.

PRECAUTIONS

METHOD OF PREPARATION FOR DEHYDRATED CULTURE MEDIA

1. Suspend 25.7gm of the dehydrated culture media in 1 liter of distilled or deionized water. Stir to mix thoroughly.

2. Heat as necessary to dissolve completely.

3. Sterilize in the autoclave at 121ºC. for 15 minutes.

PROCEDURE AND INTERPRETATION OF RESULTS

For information on procedures and interpretation of results, consult listed references or refer to the prepared media Instructions for Use (IFU) for Cat. No. K106.

LIMITATIONS

MATERIALS REQUIRED BUT NOT PROVIDED

Standard microbiological supplies and equipment such as autoclaves, incinerators, and incubators, etc., are not provided.

QUALITY CONTROL

Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Escherichia coli
ATCC ® 25922
A 18-48hr 35°C Aerobic Growth; turbidity
Staphylococcus aureus
ATCC ® 25923
A 18-48hr 35°C Aerobic Growth; turbidity
Salmonella enterica
ATCC ® 14028
A 18-48hr 35°C Aerobic Growth; turbidity

User Quality Control

PHYSICAL APPEARANCE

CRITERION™ Letheen Broth powder should appear homogeneous, moist, and lumpy, and beige in color. The prepared media should appear clear with a slight opalescence, and light to medium amber in color.

REFERENCES

1. Helrich, Kenneth, ed. 1990. Official Methods of Analysis, 15th ed. AOAC, Arlington, Virginia.

2. Marshall, R.T., ed. 1992. Standard Methods for the Examination of Dairy Products, 16th ed. APHA, Washington, D.C.

3. Vanderzant, C. and D.F. Splittstoesser, (ed.). 1992. Compendium of Methods for the Microbiological Examination of Foods, 3rd ed. APHA, Washington, D.C.

4. Greenberg, A.E., et al., (ed.). 1992. Standard Methods for the Examination of Water and Wastewater, 18th ed. APHA, Washington, D.C.

5. FDA. 1995. Bacteriological Analytical Manual , 8th ed. FDA.

6. U.S. Pharmacopeia, 22nd rev. 1990. U.S. Pharmacopeial Convention, Rockville, MD.

7. MacFaddin, J.F. 1985. Media for Isolation, Cultivation, Identification, Maintenance of Bacteria, Vol. I. Williams & Wilkins, Baltimore, MD.

8. Quality Assurance for Commercially Prepared Microbiological Culture Media, M22. Clinical and Laboratory Standards Institute (CLSI - formerly NCCLS), Wayne, PA.


ATCC is a registered trademark of the American Type Culture Collection.
Tween is a registered trademark of ICI Americas, Inc.

060616gr