Thiosulphate Citrate Bile Salts Sucrose Agar
TCBS agar is a selective as well as differential culture medium used for selective isolation of Vibrio spp from a variety of clinical and nonclinical specimens. Vibrio cholerae is the causative agent of cholera. Other Vibrio species have been associated with gastroenteritis and extraintestinal infections, especially of the ear, soft tissue, and blood.
TCBS has a very high pH (8.5-9.5) which suppresses growth of intestinal flora other than Vibrio spp. The bile salts inhibit growth of gram-positive microorganisms. Vibrio spp produce either yellow or green colonies on TCBS, depending on whether they are able to ferment sucrose. If the sucrose is fermented, yellow colonies are produced.
Vibrio cholerae produces yellow colonies in TCBS whereas Vibrio parahaemolyticus produces green colonies.