TCBS Agar

TCBS (Thiosulfate Citrate Bile Salts Sucrose) Agar medium is used for isolating and cultivating Vibrio cholerae and other enteropathogenic bacteria. TCBS is prepared according to the formula of Kobayashi et al. The pH of the medium is elevated to enhance the growth of V. cholerae. Sucrose is fermented by V. cholerae and its biotype Eltor producing yellowish-brown flat colonies. Fishbein et al. reported that V. parahaemolyticus produces light blueish colonies. Enteric and Gram-positive bacteria present in fecal specimens, including Proteus spp., are inhibited by the high concentrations of Sodium Thiosulfate and Citrate, the alkaline pH, and the presence of Bile Salts. TCBS Agar was also found useful in the isolation of V. fluvialis and V. vulnificus. Bromothymol Blue and Thymol Blue are pH indicators. Together with the fermentable sugar Sucrose, they allow to distinguish sucrose-fermenting (yellow colonies) and non-fermenting (green colonies) species.