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Fraser Broth Supplement is used with Fraser Broth Base in selectively enriching and detecting Listeria.

First described in 1926 by Murray, Webb and Swann,¹ Listeria monocytogenes is a widespread problem in public health and the food industries. This organism has the ability to cause human illness and death, particularly in immunocompromised individuals and pregnant women.² The first reported food-borne outbreak of listeriosis was in 1985,³ and since then, microbiological and epidemiological evidence from both sporadic and epidemic cases of listeriosis has indicated that the principle route of transmission is via the consumption of foods contaminated with L. monocytogenes.⁴

Implicated vehicles of transmission include turkey frankfurters,⁵ coleslaw, pasteurized milk, Mexican-style cheese, paté, and pickled pork tongue. The organism has been isolated from commercial dairy and other food processing plants, and is ubiquitous in nature, being present in a wide range of unprocessed foods as well as in soil, sewage, silage and river water.⁶

Fraser Broth Base and Fraser Broth Supplement are based on the formulation of Fraser and Sperber.⁷ The medium is used in the rapid detection of Listeria from food⁸ and environmental samples.

Many common food contaminants such as streptococci, enterococci, Bacillus spp., Escherichia coli, Pseudomonas aeruginosa and Proteus vulgaris interfere with the isolation of L. monocytogenes.⁹

Listeria species grow on laboratory media over a pH range of 4.4–9.6, and can survive in foods of similar acidity for days or weeks.¹⁰ Listeria spp. are microaerophilic, gram-positive, asporogenous, non-encapsulated, non-branching, regular, short, motile rods. Motility is most pronounced at 20°C.

Identification of Listeria is based on successful isolation of the organism, biochemical characterization and serological confirmation.

Cultural Response

Prepare Fraser Broth Base per label directions. Add Fraser Broth Supplement. Inoculate and incubate at 35 ± 2°C and read for growth and blackening at 18–24 and 42–48 h.

For Laboratory Use

Consult product labels and material safety data sheets for safety information and first aid.

Follow proper, established laboratory procedures in handling and disposing of infectious materials.