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MRCP Part 1 Infectious Diseases Facts

This article presents mrcp part 1 infectious diseases: 50 Rapid-Review Facts to sharpen your recall for the MRCP Part 1 exam. You’ll cover high-yield topics, a short exam-style case and common traps, as well as a practical study checklist from Crack Medicine.


Why this matters

Infectious diseases are a critical component of the MRCP Part 1 exam, set by The Federation of the Royal Colleges of Physicians of the UK. According to the official format page, the exam comprises two three-hour papers of 100 “best of five” MCQs each. thefederation.uk Within this, “Infectious diseases” appears as a sub-specialty with around 14 questions in the blueprint. thefederation.uk For candidates, mastering the infectious diseases section offers a reliable way to secure marks: recognition of pathogens, serology interpretation, antimicrobial principles and travel/tropical medicine. This article from Crack Medicine aims to distil key facts rapidly so you can allocate revision time efficiently.


Scope of Infectious Diseases for MRCP Part 1

Let’s clarify what you need to focus on:

  • Pathogens and mechanisms: major bacterial, viral, fungal and parasitic infections.

  • Clinical syndromes: e.g., meningitis, endocarditis, sepsis, HIV-associated infections.

  • Diagnostics: serology, culture, CSF analysis, travel history clues.

  • Therapy / resistance: antimicrobial and antiviral classes, mechanism-side-effect pairs.

  • Public health/travel/tropical: vaccinations, prophylaxis, returning traveller

    fever. For exam format reference see the official guide. thefederation.uk


50 Rapid-Review Facts (numbered list)

Here are 50 high-yield facts you can quickly review and memorise for your revision session.

  1. Mycobacterium tuberculosis forms caseating granulomas and is treated by the RIPE regimen.

  2. Ethambutol may cause optic neuritis — test colour vision if using long term.

  3. HIV: opportunistic infections appear in patterns by CD4 count thresholds.

  4. CD4 < 200 cells/mm³ → PCP (Pneumocystis jirovecii) prophylaxis indicated.

  5. HBsAg positive, anti-HBs negative, anti-HBc IgM positive → acute hepatitis B.

  6. Chronic hepatitis C may be silent and detected only via anti-HCV + HCV RNA.

  7. Infective endocarditis: S. aureus is the commonest cause in intravenous drug users.

  8. Duke criteria include major (positive blood cultures, new valvular regurgitation) and minor features.

  9. Sepsis: early recognition and prompt antibiotics within first hour improve outcomes.

  10. Malaria (Plasmodium falciparum) can cause cerebral malaria and requires urgent IV artesunate.

  11. Meningitis CSF: bacterial → low glucose (< ½ plasma), high polymorphs, high protein.

  12. Viral meningitis: lymphocytosis, normal glucose, moderate protein increase.

  13. Vaccines: live attenuated (e.g., MMR) contraindicated in severe immunosuppression.

  14. Beta-lactams inhibit cell-wall synthesis; aminoglycosides affect the 30S ribosome.

  15. Macrolides block the 50S ribosome and are useful for atypical pneumonia.

  16. Resistance: MRSA – altered penicillin-binding protein; ESBL organisms produce extended-spectrum beta-lactamases.

  17. HIV seroconversion may mimic glandular fever (fever, rash, lymphadenopathy).

  18. Travel history: consider Leishmania, dengue, chikungunya, schistosomiasis when returning.

  19. Typhoid fever: Salmonella Typhi; consider rose-spots, relative bradycardia and treat with azithromycin or ceftriaxone.

  20. Leprosy (Mycobacterium leprae): hypopigmented patches with sensory loss; treat with rifampicin + dapsone.

  21. Asplenic patients are at high risk of encapsulated organisms (e.g., pneumococcus) – lifelong penicillin prophylaxis recommended.

  22. Clostridioides difficile infection often follows broad-spectrum antibiotic use; first-line therapy is oral vancomycin.

  23. Viral hepatitis A: faeco-oral route, acute, green vomit/fever/jaundice; vaccine available.

  24. Cytomegalovirus (CMV) retinitis appears when CD4 count falls <50 cells/mm³ in HIV.

  25. Cryptococcus neoformans: causes meningitis in immunocompromised; India-ink stain or cryptococcal antigen useful.

  26. Tuberculous meningitis: CSF shows lymphocytosis, very low glucose, fibrin web; PCR more sensitive than Ziehl-Neelsen.

  27. Strongyloides stercoralis: risk of hyper-infection in steroid/immunosuppressed patients; treat with ivermectin.

  28. Schistosoma haematobium: causes haematuria and bladder cancer risk; detect eggs in urine midday.

  29. Dengue fever: think “break-bone” myalgia, rash, thrombocytopenia; serology IgM/IgG helpful.

  30. Zika virus in pregnant women: microcephaly risk; recent travellers beware.

  31. Listeria monocytogenes: gram-positive bacillus; causes meningitis in neonates, elderly and immunocompromised.

  32. Endocarditis prophylaxis is no longer routine for most dental procedures unless very high risk.

  33. Clostridium perfringens: gas gangrene; crepitus, alpha toxin; surgical emergency.

  34. Tetanus: trismus (“lock-jaw”), opisthotonus; prevention via immunisation + wound management.

  35. Leptospirosis: Weil’s disease (jaundice, renal failure, haemorrhage) after water exposure.

  36. Rabies: almost uniformly fatal once symptomatic; post-exposure prophylaxis critical.

  37. Ebola: high-mortality viral haemorrhagic fever; contact precautions essential.

  38. Influenza antiviral: oseltamivir within 48 hours; immunised high-risk groups.

  39. Pertussis (whooping cough): paroxysmal cough, “whoop”, lymphocytosis; macrolides treat.

  40. Measles: Koplik spots, rash; complications include SSPE, pneumonia.

  41. Varicella zoster: chicken-pox in children, shingles in older; treat with aciclovir, immunise older adults.

  42. Post-exposure prophylaxis for hepatitis B: HBsAg-positive source + unvaccinated → HBV immunoglobulin + vaccine.

  43. Post-exposure prophylaxis for HIV: “within 1-2 hours, up to 72 hours” of exposure.

  44. Pneumocystis jirovecii pneumonia: ground-glass appearance on CT, treat with high-dose co-trimoxazole + steroids if PaO₂ < 9.3 kPa.

  45. HSV encephalitis: temporal-lobe necrosis on MRI, treat early with IV aciclovir.

  46. Acute bacterial sinusitis most common organisms: Streptococcus pneumoniae, Haemophilus influenzae.

  47. MRSA colonisation may require nasal mupirocin + chlorhexidine body wash prior to surgery.

  48. Vancomycin-resistant Enterococcus (VRE): difficult nosocomial infection; linezolid or daptomycin used.

  49. Vaccine-preventable infections: >90 % measles elimination requires high community coverage; UK schedules matter.

  50. Multi-drug-resistant tuberculosis (MDR-TB): resistant to at least isoniazid + rifampicin; treat with second-line agents and longer duration.


Practical Example / Mini-Case

Case: A 29-year-old male with known HIV presents with dry cough, progressive dyspnoea over one week, and SpO₂ 88 % on room air. Chest-Xray shows bilateral diffuse interstitial infiltrates. CD4 count is 180 cells/mm³.Question: What is the most likely diagnosis and what is the next best step in management? Answer & Explanation: The most likely diagnosis is Pneumocystis jirovecii pneumonia (PCP). In HIV patients with CD4 <200, PCP is a common opportunistic infection. The next best step is to commence high-dose co-trimoxazole (trimethoprim-sulphamethoxazole) and add corticosteroids if PaO₂ <9.3 kPa. This is a classic pattern likely to appear in the MRCP Part 1 exam.


Stethoscope on a medical textbook with floating icons of bacteria and viruses, representing study of infectious diseases for MRCP Part 1.

Practical Study-Tip Checklist

  • ✅ Use time-boxed practice sessions via our Free MRCP MCQs bank: set 30-minute blocks focusing on infectious disease questions.

  • ✅ Build flashcards for drug-mechanism-side-effect pairs (e.g., rifampicin → orange secretions).

  • ✅ Review broad topics every 4 weeks (spaced repetition) to reinforce long-term memory.

  • ✅ After each practice block, review wrong answers and understand why distractors were incorrect.

  • ✅ Group revision around themes (e.g., tropical infections, HIV/opportunistic, antimicrobials) for pattern recognition.

  • ✅ As you progress, simulate full timed paper using Start a mock test to build stamina and exam familiarity.


Common Pitfalls and Fixes

  • Confusing serology markers: e.g., mis-interpreting hepatitis B serology — fix: draw your own diagram and revise weekly.

  • Neglecting travel history: many exam vignettes hinge on “returning traveller” clues — fix: always ask the one-sentence travel question in practice.

  • Ignoring prophylaxis questions: HIV, asplenia, splenectomy contexts often tested — fix: create a mini-list of prophylaxis scenarios.

  • Overlooking drug side-effects: e.g., ethambutol, rifampicin, linezolid — fix: create a side-effect flash-card deck.

  • Mis-prioritising time in the exam: Infectious disease questions often appear among multi-system vignettes — fix: practise timed 30-minute blocks to sharpen speed.


FAQs

Q1: How many questions on infectious diseases appear in MRCP Part 1?Approximately 14 questions out of 200 are allocated to infectious diseases according to the official blueprint. thefederation.uk

Q2: Should I focus more on travel/tropical infections or common hospital infections?

Both are important, but for MRCP Part 1 your strongest return comes from common UK-based infections (HIV, TB, endocarditis, sepsis) plus a handful of high-yield tropical/travel infections.

Q3: Are antimicrobial pharmacology questions tested in MRCP Part 1?

Yes — questions include mechanisms of action, resistance and side-effects of antibiotics, antivirals and antifungals as part of infection modules.

Q4: Is microbiology tested separately in MRCP Part 1?

No — microbiology appears integrated into clinical scenarios across specialties; it's not a standalone section but part of the infection/clinical sciences content.

Q5: How does Crack Medicine help with my preparation?

Crack Medicine offers a structured QBank, timed mock tests and lectures focusing on high-yield topics. The system supports exam-style practice, error-review and topic-specific reinforcement.


Ready to start?

Set your infectious disease revision on a solid path: begin with our Free MRCP MCQs to test recall, then use a full mock test to gauge your performance under timed conditions. Visit the main MRCP Part 1 overview page for further structured guidance and unify your study effectively.


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