Mycology: Pneumocystis pneumonia: 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 · Mycology: Pneumocystis pneumonia

Sample item

A 34-year-old man with untreated HIV (CD4 count 70 cells/mm3) has three weeks of progressive dyspnoea and dry cough. SpO2 is 86% and PaO2 is 58 mmHg on room air. Chest radiograph shows bilateral diffuse interstitial infiltrates and LDH is raised. Which treatment is most appropriate?

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

The answer and the reasoning

A. High-dose cotrimoxazole with adjunctive prednisolone

This is Pneumocystis jirovecii pneumonia, which is diagnosed by silver staining of bronchoalveolar lavage or induced sputum and supported by raised beta-D-glucan. The treatment of choice is high-dose trimethoprim-sulfamethoxazole for 21 days. Adjunctive corticosteroids reduce mortality in moderate to severe disease with PaO2 below 70 mmHg.

Option by option

  • A. High-dose cotrimoxazole with adjunctive prednisolone (correct)

    Correct. Cotrimoxazole plus steroids is indicated for hypoxaemic Pneumocystis pneumonia.

  • B. Oral fluconazole

    Fluconazole does not treat Pneumocystis.

  • C. Cotrimoxazole alone, because steroids are contraindicated in HIV

    Steroids are not contraindicated here, and omitting them raises the risk of respiratory failure.

  • D. Intravenous amphotericin B

    Amphotericin B has no useful activity against Pneumocystis, which lacks ergosterol.

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 A, High-dose cotrimoxazole with adjunctive prednisolone. This is Pneumocystis jirovecii pneumonia, which is diagnosed by silver staining of bronchoalveolar lavage or induced sputum and supported by raised beta-D-glucan.

Why is "Oral fluconazole" not the answer?

Fluconazole does not treat Pneumocystis.

Why is "Cotrimoxazole alone, because steroids are contraindicated in HIV" not the answer?

Steroids are not contraindicated here, and omitting them raises the risk of respiratory failure.

Why is "Intravenous amphotericin B" not the answer?

Amphotericin B has no useful activity against Pneumocystis, which lacks ergosterol.

What concept does this question test?

It tests Mycology: Pneumocystis pneumonia in Microbiology. The treatment of choice is high-dose trimethoprim-sulfamethoxazole for 21 days. Adjunctive corticosteroids reduce mortality in moderate to severe disease with PaO2 below 70 mmHg.

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 Mycology: Pneumocystis pneumonia?

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.