MCQ – 87478

For selective isolation of which specific intestinal pathogen is thiosulphate citrate, bile salts, sucrose agar (TCBS)recommended?

A.	Enteropathogenic Escherichia coli
B.	Salmonella typhi
C.	Shigella dysenteriae
D.	Vibrio cholerae

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Correct Answer � D Explanation

Ans.D. Vibrio cholerae

This medium was introduced for selective isolation of vibrio’s responsible for cholera ( V. cholerae and its E1 Torbiotype) and food poisoning (V.prahaemolyticus). Vibrio’s differ from the coliforms in preferring an alkaline environment with a high salt content. Such conditions are provided by TCBS medium which suppresses the growth of most other organisms in faeces and therefore greatly aids primary isolation of vibrios. Colonies of V. cholerae and El Tor biotype form butter yellow colonies within 24 hours and V. parahaemolyticus can be distinguished by forming colonies with greenish-blue centres.