Citrate Azide Tween Carbonate Base, 500G

Enterococci may be considered an essential part of the autochthonous microflora of humans and animals. Because of its wide distribution, Enterococci can also occur in different food commodities, especially those of animal origin (1).! Enterococcus faecalis and Enterococcus faecium are relatively heat-resistant and may characteristically survive in traditional milk pasteurization procedures. E. faecium is markedly heat-tolerant and is a spoilage agent in marginally processed canned hams. Most of the Enterococci are relatively resistant to freezing, and, unlike Escherichia coli @, they readily survive this treatment (2). A wide variety of selective media for Enterococcus has been recommended and used. Indicator substances added to the media are useful for the recognition of Enterococci and for the rapid identification of single species on the basis of colony appearance. Citrate Azide Tween Carbonate Base is a selective media formulated by Burkwall and Hartmann (3). It was later modified by Reuter (4) for the identification of Enterococci in meat, meat products, dairy products and other foodstuffs. Casein enzymic hydrolysate and yeast extract in the medium provide nitrogen, vitamins and amino acids. Tween 80 acts as a neutralizer, which inactivates residual disinfectants if present in the collected sample. The high concentrations of citrate inhibit the growth of the accompanying microbial flora. Triphenyl Tetrazolium Chloride (TTC) is reduced by Enterococci to form a red formazan, which imparts red color to the colonies. Sodium azide helps in the selective isolation of Enterococci. The test sample can be directly streaked on the surface of the agar. Appearance: Cream to yellow homogeneous free flowing powder Gelling: Firm, comparable with 1.5% Agar gel Color and Clarity of prepared medium: Yellow colored, clear to slightly opalescent gel forms in Petri plates