Culture media: enrichment broth: practice question

A Microbiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Microbiology · Culture media: enrichment broth

Sample item

A food handler is suspected to be a carrier of Salmonella, and a stool sample contains abundant coliforms. Which medium is used first to favour growth of Salmonella before plating on a selective agar?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. Selenite F broth

Enrichment media allow the pathogen to multiply while suppressing normal flora. Selenite F broth inhibits coliforms for several hours and is used for Salmonella and some Shigella from stool before subculture on deoxycholate citrate or xylose lysine deoxycholate agar.

Option by option

  • A. Robertson cooked meat medium

    Robertson cooked meat medium supports anaerobes such as clostridia.

  • B. Alkaline peptone water

    Alkaline peptone water is the enrichment medium for Vibrio cholerae.

  • C. Loeffler serum slope

    Loeffler serum slope is used to grow Corynebacterium diphtheriae and show its granules.

  • D. Selenite F broth (correct)

    Selenite F suppresses coliforms and enriches Salmonella from faeces.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Microbiology question

What is the answer to this Microbiology question?

The best answer is D, Selenite F broth. Enrichment media allow the pathogen to multiply while suppressing normal flora.

Why is "Robertson cooked meat medium" not the answer?

Robertson cooked meat medium supports anaerobes such as clostridia.

Why is "Alkaline peptone water" not the answer?

Alkaline peptone water is the enrichment medium for Vibrio cholerae.

Why is "Loeffler serum slope" not the answer?

Loeffler serum slope is used to grow Corynebacterium diphtheriae and show its granules.

What concept does this question test?

It tests Culture media: enrichment broth in Microbiology. Selenite F broth inhibits coliforms for several hours and is used for Salmonella and some Shigella from stool before subculture on deoxycholate citrate or xylose lysine deoxycholate agar.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Culture media: enrichment broth?

Make a one-line identity card for each organism: shape and stain, defining test, toxin, disease and drug. Then use the flashcards and the other Microbiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.