Selenite cystine broth (7283)

FRASER BROTH (7626)
Intended Use
Fraser Broth is used with acriflavin, nalidixic acid and ferric ammonium citrate for the selective enrichment of
Listeria spp.
Product Summary and Explanation
Listeria monocytogenes, described first in 1926 by Murray, Webb and Swann, is an extensive problem in
public health and food industries.1 This organism has the ability to cause human illness and death, particularly
in immunocompromised individuals and pregnant women.2 Epidemiological evidence from outbreaks of
listeriosis indicated the principle route of transmission is via the consumption of foodstuffs contaminated with
Listeria monocytogenes.3 Implicated vehicles of transmission include turkey frankfurters,.coleslaw,
pasteurized milk, Mexican style cheese and pate′.4 Listeria spp. are ubiquitous in nature, present in a wide
range of unprocessed foods and in soil, sewage, and river water.5 Fraser Broth is based on the formulation of Fraser and Sperber.6 This medium is used in rapid detection ofListeria from food7 and environmental samples. Listeria spp. grow over a pH range of 5.0 - 9.6, and survive infood products with pH levels outside these parameters.8 Listeria spp. are microaerophilic, Gram-positive,asporogenous, non-encapsulated, non-branching, short, motile rods. Motility is pronounced at 20°C.
Identification of Listeria spp. is based on successful isolation of the organism, biochemical characterization,and serological confirmation.
Principles of the Procedure
Enzymatic Digest of Casein, Enzymatic Digest of Animal Tissue, Beef Extract, and Yeast Extract provide
nitrogen, vitamins and minerals in Fraser Broth. The Phosphates are the buffering agents, Sodium Chloride
maintains osmotic balance. Differentiation is aided by including Ferric Ammonium Citrate in the final medium.
Since all Listeria species hydrolyze esculin, the addition of ferric ions to the medium will detect the reaction.
Blackening of the medium by esculin-hydrolyzing bacteria is a result of formation of 6,7-dihydroxycoumarin
that reacts with ferric ions.6 Selectivity is provided by the presence of Lithium Chloride, Nalidixic Acid and
Acriflavin in the formula. The high salt tolerance of Listeria spp. is used to inhibit growth of enterococci.
Formula / Liter
Supplement / 10 mL
Yeast Extract.5 gSodium Chloride .20 gDisodium Phosphate.12 gMonopotassium Phosphate .1.35 gEsculin .1 gLithium Chloride .3 gFinal pH: 7.3 ± 0.2 at 25ºCFormula may be adjusted and/or supplemented as required to meet performance specifications.
Precautions
1. For Laboratory Use.
2. TOXIC. Irritating to eyes, respiratory system, and skin.
Directions
1. Dissolve 57.4 g of the medium in one liter of purified water.
2. Heat with frequent agitation and boil for one minute to dissolve completely.
3. Autoclave at 121°C for 15 minutes. Cool broth to room temperature.
4. Aseptically add 10 mL of a filter sterilized solution containing 0.5 g ferric ammonium citrate, 20 mg nalidixic acid and 25 mg acriflavin.
Quality Control Specifications
Dehydrated Appearance: Powder is homogeneous, free flowing, and tan.
Prepared Appearance: Prepared medium is medium amber, clear to slightly opalescent with a fine
precipitate.
Expected Cultural Response: Cultural response in Fraser Broth at 35°C after 18 - 48 hours incubation.
Microorganism
Response
Listeria monocytogenes ATCC 7644 Listeria monocytogenes ATCC 15313 Staphylococcus aureus ATCC 25923 The organisms listed are the minimum that should be used for quality control testing.
Test Procedure
To isolate Listeria monocytogenes from processed meats and poultry, the following procedure is
recommended by the U.S.D.A.7
1. Add 25 g of test material to 225 mL of UVM Modified Listeria Enrichment Broth and mix or blend
thoroughly. Incubate for 20 - 24 hours at 30°C.
2. Transfer 0.1 mL of the incubate broth to Fraser Broth. Incubate at 35°C for 26 ± 2 hours.
3. At 24 and 48 hours, streak the Fraser Broth culture to Modified Oxford Agar. Incubate the Modified Oxford plates at 35°C for 24 - 48 hours.
Results
1. Examine agar plates for suspect colonies. For complete identification and confirmation of Listeria spp.,
consult appropriate references.7-10
2. Rapid slide and macroscopic tube tests can be used for definitive serological identification.
Storage
Store sealed bottle containing the dehydrated medium at 2 - 30°C. Once opened and recapped, place
container in a low humidity environment at the same storage temperature. Protect from moisture and light by
keeping container tightly closed.
Expiration
Refer to expiration date stamped on the container. The dehydrated medium should be discarded if not free
flowing, or if appearance has changed from the original color. Expiry applies to medium in intact container
when stored as directed.
Limitation of the Procedure
An identification of Listeria monocytogenes must be confirmed by biochemical and serological testing.9,10
Packaging
Fraser Broth
References
1.
Murray, E. G. D., R. A. Webb, and M. B. R. Swann. 1926. A disease of rabbits characterized by large mononuclear leucocytosis caused by ahitherto
undescribed bacillus Bacterium monocytogenes. J. Path. Bact. 29:407-439.
Monk, J. D., R. S. Clavero, L. R. Beuchat, M. P. Doyle, and R. E. Brackett. 1994. Irradiation inactivation of Listeria monocytogenes and
Staphylococcus aureus in low and high fat, frozen refrigerated ground beef. J. Food Prot. 57:969-974.
Bremer, P. J., and C. M. Osborne. 1995. Thermal-death times of Listeria monocytogenes in green shell mussels prepared for hot smoking. J. Food
Prot. 58:604-608.
Grau, F. H., and P. B. Vanderlinde. 1992. Occurrence, numbers, and growth of Listeria monocytogenes on some vacuum-packaged processed meats.
J. Food Prot. 55:4-7.
Patel, J. R., C. A. Hwang, L. R. Beuchat, M. P. Doyle, and R. E. Brackett. 1995. Comparison of oxygen scavengers for their ability to enhance
resuscitation of heat-injured Listeria monocytogenes. J. Food Prot. 58:244-250.
Fraser, J., and W. Sperber. 1988. Rapid detection of Listeria in food and environmental samples by esculin hydrolysis. J. Food Prot. 51:762-765.
Lee, W. H., and D. McClain. 1994. Laboratory Communication No. 57, U.S.D.A., F.S.I.S. Microbiology Division, Bethesda, MD.
Vanderzant, C., and D. F. Splittstoesser (eds.). Compendium of methods for the microbiological examination of foods, 3rd ed. American Public Health
Association, Washington, D.C.
Murray, P. R., E. J. Baron, M. A. Pfaller, F. C. Tenover, and R. H. Yolken (eds.). Manual of clinical microbiology, 6th ed. American Society for
Microbiology, Washington, D.C.
10. Marshall, R. T. (ed.). Standard methods for the examination of dairy products 16th ed., American Public Health Association, Washington D.C.
Technical Information
Contact Acumedia Manufacturers, Inc. for Technical Service or questions involving dehydrated culture media preparation or
performance at (410)780-5120 or fax us at (410)780-5470.

Source: http://www.jsunitech.com/product/culture/manual/Fraser%20Broth.pdf