Thiosulfate Citrate Bile Salts Sucrose Agar (TCBS Agar) is used for the selective isolation of cholera vibrios and Vibrio parahaemolyticus from a variety of clinical and nonclinical specimens.
SUMMARY AND EXPLANATION
Vibrio species are most widely recognized for their role in human intestinal infections. Diarrheas caused by Vibro cholerae and V. parahaemolyticus are important worldwide. The isolation of Vibrio species has been enhanced by the development of media which are highly selective for vibrios.
TCBS is the primary plating medium universally used for the selective isolation of vibrios that cause cholera, diarrhea and food poisoning. It was developed by Kobayashi et al., who modified the selective medium of Nakanishi. The combination of alkaline peptone water and TCBS Agar is used in many procedures for the isolation of V. cholerae and other Vibrio species from feces.
TCBS Agar Deeps (pour tubes) are provided in a 20 mL fill so that the medium may be liquefied and poured into a Petri dish. This provides a convenient source of medium with a longer shelf-life than pre-poured plated media.
TCBS Agar is highly selective for the isolation of V. cholerae and V. parahaemolyticus as well as other vibrios. Inhibition of gram-positive bacteria is achieved by the incorporation of oxgall, which is a naturally occurring substance containing a mixture of bile salts, and sodium cholate, a pure bile salt. Sodium thiosulfate serves as a sulfur source and, in combination with ferric citrate, detects hydrogen sulfide production. Saccharose (sucrose) is included as a fermentable carbohydrate for the metabolism of vibrios. The alkaline pH of the medium enhances the recovery of V. cholerae. Thymol blue and bromthymol blue are included as indicators of pH changes.
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