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MRCP Part 1 Infectious Diseases MCQs & Explanations

TL;DR

This article covers mrcp part 1 infectious diseases — 25 practice mcqs with explanations, summarising the most tested areas, essential patterns, and classic exam traps. It also includes a detailed sample MCQ with reasoning, a study checklist, and links to further revision. Infectious Diseases contributes a consistent number of marks in MRCP Part 1, especially through integrated microbiology and general medicine scenarios. Use the structured notes and pitfalls below to sharpen your exam technique.


Why this matters

In MRCP Part 1, Infectious Diseases (ID) appears across Microbiology, Respiratory, Neurology, Gastroenterology, Tropical Medicine, and Clinical Pharmacology. The exam rarely tests obscure pathogens—instead it rewards pattern recognition, correct interpretation of serology, and safe first-line management based on UK practice.

The MRCP(UK) blueprint confirms regular testing of pneumonia, meningitis, HIV, TB, viral hepatitis, sepsis, and antimicrobial stewardship. For wider context, see the MRCP Part 1 overview (/mrcp-part-1/).


High-yield exam areas in Infectious Diseases

A concise outline of the most consistently tested topics:

  1. Pneumonia (CAP, HAP, atypicals)

  2. Meningitis & encephalitis

    • Immediate antibiotics do not wait for LP if unsafe.

    • HSV encephalitis → early IV aciclovir.

  3. Tuberculosis (UK practice)

  4. HIV & opportunistic infections

  5. Viral hepatitis (B & C)

  6. Sepsis & antimicrobial stewardship

    • Early recognition and appropriate cultures.

    • Narrow therapy based on sensitivities.

  7. Tropical Medicine

  8. Vaccines & PEP

    • Live vaccines (MMR, varicella).

    • HBV PEP for needle-sticks based on immunity.


Quick-reference table: 10 pattern-recognition triggers for the exam

Clinical Clue

Likely Diagnosis

Exam Pearl

Hyponatraemia + pneumonia

Legionella

Think atypical; macrolide/quinolone coverage.

Dry cough + ↑LDH in HIV

PCP

Treat with high-dose co-trimoxazole +/- steroids.

Petechiae + fever

Meningococcal infection

Give immediate IV antibiotics.

Fever after travel + thrombocytopenia

Malaria

Urgent rapid test & thick/thin films.

Chronic cough + cavitation

TB

Consider sputum AFB & IGRA.

Back pain + recent bacteraemia

Vertebral osteomyelitis

MRI spine.

Hepatitis B “window period”

acute infection

Anti-HBc IgM positive.

Animal exposure + fever + AKI

Leptospirosis

Serology helpful; treat with doxycycline.

New murmur + fever

Endocarditis

Obtain 3 sets of blood cultures.

Severe sore throat + membrane

Diphtheria

Rare but classic; public health involvement.

Practical examples / mini-case


Sample MCQ with explanation

A 32-year-old man with HIV (CD4 120) presents with 10 days of progressive dyspnoea, dry cough, and low-grade fever. Oxygen saturations fall from 96% at rest to 86% when walking. Chest X-ray shows diffuse bilateral interstitial infiltrates. LDH is elevated. What is the most appropriate initial management?


A. Oral doxycyclineB. IV co-amoxiclavC. High-dose oral co-trimoxazoleD. Nebulised pentamidineE. Oral prednisolone alone

Correct answer: C. High-dose oral co-trimoxazole

Explanation: The presentation is classic for Pneumocystis jirovecii pneumonia (PCP)—progressive dyspnoea, exertional desaturation, bilateral interstitial infiltrates, and high LDH in an immunocompromised patient. First-line therapy in the UK is high-dose co-trimoxazole. Steroids may be added depending on oxygenation status but are not used alone. Pentamidine is a second-line option.


Study-tip checklist for Infectious Diseases (Exam-Oriented)

  1. Know the “red-flag” presentations that mandate immediate therapy (meningococcal disease, severe CAP, severe malaria).

  2. Practise serology decoding for HBV, HCV, EBV, and syphilis.

  3. Review antimicrobial first-line options from NICE and UKHSA—MRCP Part 1 favours UK consensus.

  4. Remember that in sepsis, antibiotics should not be delayed for imaging.

  5. Memorise TB drug toxicities and their matching patterns.

  6. Track common drug–drug interactions in HIV.

  7. Identify typical travel-related fevers and their hallmark laboratory clues.

  8. Use spaced repetition for microbiology details; avoid memorising rare pathogens.

  9. Practise 50–100 timed ID questions per week.

  10. Integrate ID with respiratory and neurology questions—MRCP integrates systems heavily.

Clinician reviewing MRCP Part 1 Infectious Diseases MCQs on a digital device

Five common pitfalls (and how to fix them)

  1. Over-emphasising pathogen lists→ Focus instead on patterns, first presentations, and UK-first-line therapy.

  2. Misinterpreting hepatitis B serology→ Always start with: HBsAg? anti-HBc IgM? anti-HBs?

  3. Missing sepsis in atypical presentations→ Remember older adults and diabetics may lack fever.

  4. Undertreating malaria severity→ Any P. falciparum infection = high risk; urgently check parasitaemia.

  5. Confusing TB drug side effects→ Build a small mnemonic list and revise weekly.


FAQs (People Also Ask)

1. How many Infectious Diseases questions appear in MRCP Part 1?

The exact numbers vary, but typically 10–15% of the paper touches ID themes, especially pneumonia, meningitis, HIV, TB, hepatitis, malaria, and stewardship. The MRCP(UK) blueprint confirms recurring weighting across infection-related systems.

2. What is the best way to learn complex serology patterns?

Use structured tables and repeat exposure. Practice with questions in the Free MRCP MCQs (/qbank/) section helps reinforce HBV/HCV patterns in real exam formats.

3. Are tropical infections frequently tested?

Yes—malaria, dengue, typhoid, and leptospirosis appear regularly, often through travel histories. WHO guidance assists with high-level clinical features.

4. Should I memorise rare pathogens?

Not necessary. MRCP Part 1 focuses on common diseases and high-risk situations. Recognising key patterns is far more valuable than rote lists.

5. How can I improve speed in ID questions?

Practise timed blocks and review your error patterns weekly. The Start a mock test (/mock-tests/) section is ideal for practising exam pacing.


Ready to start?

If you found this useful, explore our MRCP Part 1 overview (/mrcp-part-1/) for structured revision plans, try the Free MRCP MCQs (/qbank/) for daily practice, or attempt a timed exam in Start a mock test (/mock-tests/). Consistent, pattern-based revision makes Infectious Diseases one of the most rewarding sections of MRCP Part 1.


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