A 24-year-old man develops profuse painless watery diarrhoea with flecks of mucus after eating seafood. Stool shows no pus cells or red cells. Which culture medium should be inoculated to isolate the causative agent?
- A MacConkey agar
- B Thiosulfate citrate bile salts sucrose (TCBS) agar ✓
- C XLD agar
- D Loeffler serum slope
Correct answer: B. Thiosulfate citrate bile salts sucrose (TCBS) agar
Explanation
Rice-watery stool without inflammatory cells after seafood points to Vibrio cholerae. TCBS agar is the selective medium: cholerae strains ferment sucrose and appear as yellow convex colonies, while V. parahaemolyticus forms green colonies. MacConkey supports many Enterobacterales but inhibits vibrios poorly selectively and XLD targets Salmonella and Shigella, which cause inflammatory bloody stools. Loeffler slope is used for diphtheria bacilli and has no role here.
Reference: Ananthanarayan and Paniker's Textbook of Microbiology, 12th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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