TCBS AGAR (SELECTIVE)

Description

TCBS Agar was developed by Kobayashi et al, who modified the selective medium of Nakanishi. Although this medium was originally designed for the isolation of V. cholerae and V. parahaemolyticus, most Vibrios grow to healthy large colonies with many different colonial morphologies. TCBS Agar is also recommended by APHA for the selective isolation of V.cholerae and V.parahaemolyticus. Enrichment in Alkaline Peptone Water, followed by isolation on TCBS Agar is routinely used for isolation of V.cholerae. TCBS Agar, Selective has an additional selective ingredient i.e. sodium cholate for improved selectivity. TCBS Agar is not a suitable medium for oxidase testing of Vibrio species. A few strains of V. cholerae may appear green or colourless on TCBS Agar due to delayed sucrose fermentation. TCBS Agar is highly selective for Vibrio species. However, occasional isolates of Pseudomonas and Aeromonas may also form blue green colonies on TCBS Agar. Any H2S negative colony of TCBS Agar can be considered presumptive positive for Vibrio.