Transport of Vibrio cholerae from field to lab: Which transport medium is appropriate for maintaining viability of V. cholerae during transit?

Introduction:
Proper transport media preserve enteric pathogens during sample transit, preventing overgrowth and die-off. This question assesses recognition of suitable media for Vibrio cholerae.

Given Data / Assumptions:

• Stools or rectal swabs must maintain V. cholerae viability until plating on selective media.
• Certain media are designed specifically as transport, not enrichment.
• Multiple named media may appear in exams.

Concept / Approach:
Identify transport media validated for V. cholerae. VR medium and Cary–Blair are recognized options. Enrichment broths for Salmonella (selenite F, tetrathionate) and plain nutrient broth are unsuitable as transport for cholera specimens.

Step-by-Step Solution:
Step 1: Recall that Venkatraman–Ramakrishnan (VR) is a traditional transport medium for V. cholerae in endemic regions.Step 2: Recognize Cary–Blair as a widely used general transport medium suitable for Vibrio as well.Step 3: Exclude Salmonella enrichment broths and nutrient broth for transport purposes.Step 4: Choose VR as the best single answer because it is explicitly formulated for V. cholerae transport.

Verification / Alternative check:
Laboratory references from endemic settings list VR and Cary–Blair as acceptable transport media; many exam keys favor VR when a single best answer is required.

Why Other Options Are Wrong:

• Selenite F and tetrathionate: enrichment for Salmonella; inappropriate as transport for Vibrio.
• Nutrient broth: lacks buffering/selectivity; overgrowth and loss of pathogen likely.
• Cary–Blair: acceptable in practice, but when one answer is expected, VR is the classic named choice for V. cholerae.

Common Pitfalls:
Confusing enrichment with transport; assuming any broth will suffice for specimen preservation.

Final Answer:
Venkatraman–Ramakrishnan (VR) transport medium.