Clinical microbiology and hospital infection control: IMViC: 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.

Try it

Microbiology · Clinical microbiology and hospital infection control: IMViC

Sample item

Two lactose-fermenting Gram-negative bacilli grow from a urine culture. Isolate A is indole positive and methyl red positive, and isolate B is indole negative, methyl red negative and Voges-Proskauer positive. Which pair is correct?

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

The answer and the reasoning

C. A is Escherichia coli and B is Klebsiella pneumoniae

E. coli follows the IMViC pattern ++-- (indole and methyl red positive), whereas Klebsiella is --++ (VP and citrate positive). Proteus and Shigella are non-lactose fermenters, so they cannot be either isolate.

Option by option

  • A. A is Proteus mirabilis and B is Escherichia coli

    Proteus is a non-lactose fermenter.

  • B. A is Klebsiella pneumoniae and B is Escherichia coli

    The pairs are reversed in this option.

  • C. A is Escherichia coli and B is Klebsiella pneumoniae (correct)

    Correct. ++-- is E. coli and --++ is Klebsiella.

  • D. A is Enterobacter cloacae and B is Shigella sonnei

    Shigella is a non-lactose fermenter.

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.

More Microbiology questions

Questions about this Microbiology question

What is the answer to this Microbiology question?

The best answer is C, A is Escherichia coli and B is Klebsiella pneumoniae. E.

Why is "A is Proteus mirabilis and B is Escherichia coli" not the answer?

Proteus is a non-lactose fermenter.

Why is "A is Klebsiella pneumoniae and B is Escherichia coli" not the answer?

The pairs are reversed in this option.

Why is "A is Enterobacter cloacae and B is Shigella sonnei" not the answer?

Shigella is a non-lactose fermenter.

What concept does this question test?

It tests Clinical microbiology and hospital infection control: IMViC in Microbiology. coli follows the IMViC pattern ++-- (indole and methyl red positive), whereas Klebsiella is --++ (VP and citrate positive). Proteus and Shigella are non-lactose fermenters, so they cannot be either isolate.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 Clinical microbiology and hospital infection control: IMViC?

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.