Chronic inflammation: actinomycosis: practice question

A Pathology 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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Pathology · Chronic inflammation: actinomycosis

Sample item

After a dental extraction, a 40-year-old man develops a firm swelling of the lower jaw with multiple draining sinuses discharging yellow granules. Crushed granules show Gram-positive branching filaments that are not acid-fast. Which organism is responsible?

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

The answer and the reasoning

B. Actinomyces israelii

Actinomyces israelii is an anaerobic commensal of the mouth that causes cervicofacial suppuration with sulphur granules after trauma. The filaments are Gram-positive and not acid-fast, and treatment is prolonged penicillin with drainage. Nocardia is aerobic and weakly acid-fast on modified stains.

Option by option

  • A. Nocardia asteroides

    Nocardia is aerobic, partly acid-fast, and typically causes lung or brain abscess.

  • B. Actinomyces israelii (correct)

    Anaerobic non-acid-fast branching filaments forming sulphur granules in the jaw point to Actinomyces.

  • C. Mycobacterium tuberculosis

    Tubercle bacilli are acid-fast rods and do not form branching filaments or sulphur granules.

  • D. Madurella mycetomatis

    Madurella is a fungus causing eumycetoma, usually of the foot, with grains made of true hyphae.

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 Pathology question

What is the answer to this Pathology question?

The best answer is B, Actinomyces israelii. Actinomyces israelii is an anaerobic commensal of the mouth that causes cervicofacial suppuration with sulphur granules after trauma.

Why is "Nocardia asteroides" not the answer?

Nocardia is aerobic, partly acid-fast, and typically causes lung or brain abscess.

Why is "Mycobacterium tuberculosis" not the answer?

Tubercle bacilli are acid-fast rods and do not form branching filaments or sulphur granules.

Why is "Madurella mycetomatis" not the answer?

Madurella is a fungus causing eumycetoma, usually of the foot, with grains made of true hyphae.

What concept does this question test?

It tests Chronic inflammation: actinomycosis in Pathology. The filaments are Gram-positive and not acid-fast, and treatment is prolonged penicillin with drainage. Nocardia is aerobic and weakly acid-fast on modified stains.

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 Chronic inflammation: actinomycosis?

Learn each disease as a bundle: cause, key histology, markers, and the clinical hallmark. Then use the flashcards and the other Pathology 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.