Bacteriology: 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 · Bacteriology

Sample item

A pregnant woman develops fever and diarrhoea after eating unpasteurised soft cheese. Her newborn develops meningitis. Gram stain of CSF shows small Gram-positive rods that show tumbling motility at room temperature. What is the organism?

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

The answer and the reasoning

C. Listeria monocytogenes

Listeria monocytogenes is a motile Gram-positive bacillus that grows at refrigeration temperature (cold enrichment), shows tumbling motility at 25 degrees C and causes neonatal meningitis and sepsis after maternal infection from contaminated dairy products. Ampicillin is a key drug.

Option by option

  • A. Corynebacterium diphtheriae

    Corynebacterium diphtheriae is non-motile and causes pharyngeal pseudomembrane.

  • B. Clostridium perfringens

    Clostridium perfringens is non-motile and causes gas gangrene and food poisoning.

  • C. Listeria monocytogenes (correct)

    Correct. Tumbling motility, cold growth and dairy exposure point to Listeria.

  • D. Bacillus cereus

    Bacillus cereus causes food poisoning from rice and is a larger rod that forms spores.

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, Listeria monocytogenes. Listeria monocytogenes is a motile Gram-positive bacillus that grows at refrigeration temperature (cold enrichment), shows tumbling motility at 25 degrees C and causes neonatal meningitis and sepsis after maternal infection from contaminated dairy products.

Why is "Corynebacterium diphtheriae" not the answer?

Corynebacterium diphtheriae is non-motile and causes pharyngeal pseudomembrane.

Why is "Clostridium perfringens" not the answer?

Clostridium perfringens is non-motile and causes gas gangrene and food poisoning.

Why is "Bacillus cereus" not the answer?

Bacillus cereus causes food poisoning from rice and is a larger rod that forms spores.

What concept does this question test?

It tests Bacteriology in Microbiology. Ampicillin is a key drug.

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 Bacteriology?

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.