LAURYL TRYPTOSE BROTH

Cat. no. K33 Lauryl Tryptose Broth with Durham Tube, 20x125mm Tube, 13ml 20 tubes/box
Cat. no. K32* Lauryl Tryptose Broth with Durham Tube DS, 20x125mm Tube, 10ml 20 tubes/box
Cat. no. K35 Lauryl Sulfate Broth with MUG (Durham Tube), 16x125mm Tube, 10ml 20 tubes/box
Cat. no. K61 Lauryl Tryptose Broth with Durham Tube, 16x125mm Tube, 10ml 20 tubes/box
Cat. no. K238 Lauryl Tryptose Broth with MUG (Durham Tube), 20x125mm Tube, 10ml 20 tubes/box
Cat. no. K338* Lauryl Tryptose Broth with MUG DS (Durham Tube), 20x150mm Tube, 10ml 20 tubes/box

* Cat. nos. K32 and K338 are a double strength (DS) formulation of Lauryl Tryptose Broth.

INTENDED USE

Hardy Diagnostics Lauryl Tryptose Broth (also known as Lauryl Sulfate Broth) is recommended for use in the detection of coliforms in water, waste water, and foods.

This product is not intended to be used for the diagnosis of human disease.

SUMMARY

Lauryl Tryptose Broth is prepared according to the formulation of Mallmann and Darby.(11) Sodium lauryl sulfate, by inhibiting most gram-positive microorganisms, serves as a selective agent for coliforms. The addition of lactose to the medium allows for detection of rapid lactose fermentation by coliforms. Essential growth ingredients are provided by casein peptone which is composed of nitrogen, carbon compounds, sulfur, and trace ingredients. Potassium phosphate acts as a buffer, while sodium chloride serves to maintain osmotic equilibrium. A durham tube is present in order to detect the production of gas.

Coliforms grown in Lauryl Tryptose Broth ferment lactose and produce gas. Other bacteria are either inhibited or grow without producing gas.

Coliforms grown in Lauryl Tryptose Broth ferment lactose and produce gas. Other bacteria are either inhibited or grow without producing gas.

The addition of MUG, a fluorogenic compound, allows for the rapid detection of E. coli when the medium is observed for fluorescence using a long-wave (366nm) UV light source.(13-14) Anaerogenic strains of E. coli can also be detected through the use of MUG.(13)

The detection of E. coli with MUG is based on the ability of ß-glucuronidase, an enzyme possessed by most E. coli strains, to hydrolyze 4-methylumbelliferyl-ß-D-glucuronide. The hydrolysis of MUG by E. coli yields 4-methylumbelliferone, a fluorescent end product.(13-14) 

FORMULA

Ingredients per liter of deionized water:*

Tryptose 20.0gm
Lactose 5.0gm
Sodium Chloride 5.0gm
Monopotassium Phosphate 2.75gm
Dipotassium Phosphate 2.75gm
Sodium Lauryl Sulfate 0.1gm

Additionally, Cat. nos. K32 and K338 contain twice the concentration of the above formulation.

In addition, Cat. nos. K35, K238, and K338 also contain 0.05g of MUG (4-methylumbelliferyl-ß-D-glucuronide)

Final pH 6.8 +/- 0.2 at 25ºC.

Final pH for Cat. nos. K238 and K338 is 6.6-7.1 at 25ºC.

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

STORAGE AND SHELF LIFE

Storage: Upon receipt store at 2-30ºC (except K35, K238, and K338 which should be stored at 2-8ºC) away from direct light. Products should not be used if there are any signs of contamination, deterioration, or if the expiration date has passed. Protect from light, excessive heat, moisture, and freezing.

PRECAUTIONS

PROCEDURE

Specimen Collection: Consult listed references for information on specimen collection.(1-4,6) Samples should be submitted directly to the laboratory without delay and protected from excessive heat and cold.

Note: Refrigerated Lauryl Tryptose Broth can become cloudy or form a precipitate. Incubate medium overnight at room temperature (20ºC) before use to clear the medium.(10)

Method of Use: Please refer to the listed references for official procedures concerning the detection and enumeration of coliforms from water and food samples.(9,10,12)

Incubate inoculated medium aerobically at 35ºC for 48 hours. Examine tube for growth and gas production at 24 and 48 hours.

INTERPRETATION OF RESULTS

Turbidity with gas production within 48 hours of incubation is a positive test for the presence of coliforms. Gas production is indicated by the appearance of bubbles in the durham tube.

LIMITATIONS

Turbidity without gas production is not indicative of a positive test.

A bubble in the durham tube with no turbidity present in the broth is not indicative of a positive test.

A precipitate or cloudiness may form in refrigerated broth. Media will become clear when warmed to room temperature.

Prior to inoculation of the medium, it may be necessary to invert the tube in order to release any bubbles that may be trapped in the durham tube. Bubbles that are not removed before inoculation may lead to false-positive results.

MATERIALS REQUIRED BUT NOT PROVIDED

Standard microbiological supplies and equipment such as loops, other culture media, swabs, applicator sticks, incinerators, and incubators, etc., as well as serological and biochemical reagents, are not provided.

QUALITY CONTROL

Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Lauryl Tryptose Broth with Durham Tube (Cat. nos. K32, K33, and K61)
Escherichia coli
ATCC ® 25922
A 24hr 35°C Aerobic Growth; gas bubble in durham tube
Enterobacter aerogenes
ATCC ® 13048
A 24hr 35°C Aerobic Growth; weak gas bubble in durham tube at 48 hours
Salmonella enterica
ATCC ® 14028
A 48hr 35°C Aerobic Growth; no gas production
Serratia marcescens
ATCC ® 8100
A 48hr 35°C Aerobic Growth; no gas production
Staphylococcus aureus
ATCC ® 25923
B 48hr 35°C Aerobic Complete inhibition at 24 hrs, partial inhibition at 48 hrs; no gas production
Lauryl Tryptose Broth with MUG (Cat. no. K238 and K338); *Cat. no. K35 is tested with the below, except S. aureus
Escherichia coli
ATCC ® 25922
A 24hr 35°C Aerobic Growth; gas bubble in durham tube;  fluorescence
Klebsiella pneumoniae
ATCC ® 13883
A 24hr 35°C Aerobic Growth; gas bubble in durham tube; no fluorescence
Shigella flexneri      
ATCC ® 12022
A 24hr 35°C Aerobic Growth; no gas production; no fluorescence
Staphylococcus aureus*
ATCC ® 25923
B 24hr 35°C Aerobic Partial to complete inhibition; no gas production; no fluorescence

User Quality Control

PHYSICAL APPEARANCE

Lauryl Tryptose Broth with or without MUG should appear clear, and amber in color.

REFERENCES

1. Anderson, N.L., et al. Cumitech 3B; Quality Systems in the Clinical Microbiology Laboratory, Coordinating ed., A.S. Weissfeld. American Society for Microbiology, Washington, D.C.

2. Versalovic, J., et al. Manual of Clinical Microbiology. American Society for Microbiology, Washington, D.C.

3.Tille, P., et al. Bailey and Scott's Diagnostic Microbiology, C.V. Mosby Company, St. Louis, MO.

4. Isenberg, H.D. Clinical Microbiology Procedures Handbook, Vol. I, II & III. American Society for Microbiology, Washington, D.C.

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

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

7. Koneman, E.W., et al. Color Atlas and Textbook of Diagnostic Microbiology, J.B. Lippincott Company, Philadelphia, PA.

8.The Official Compendia of Standards. USP27-NF22. United States Pharmacopeial Convention, Rockville, MD.

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

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

11. Mallmann, W.L. and C.W. Darby. Am. J. Publ. Health; 31:127, 941.

12. Association of Official Analytical Chemists. Official Methods of Analysissm, AOAC, Washington, D.C.

13. Feng and Hartman. 1982. Appl. Environ. Microbiol.; 43:1320.

14. Robison. 1984. Appl. Environ. Microbiol.; 48:285.

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

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