Infective Endocarditis: High-Yield Essentials
Infective Endocarditis (IE) involves microbial infection of the heart valves or endocardium. For NEET PG, focus heavily on the causative organisms, clinical diagnostic criteria (Modified Duke), and complications.
1. High-Yield Microbiology
| Scenario | Common Pathogen |
|---|---|
| Community-acquired (Native Valve) | Staphylococcus aureus (most common overall) or Viridans group Streptococci (post-dental). |
| Prosthetic Valve (< 60 days) | Staphylococcus epidermidis. |
| IV Drug Users (IVDU) | S. aureus (often tricuspid valve). |
| Colorectal Cancer/UC | Streptococcus gallolyticus (formerly S. bovis). |
2. Modified Duke Criteria (Diagnostic Pillars)
Diagnosis requires 2 major, 1 major + 3 minor, or 5 minor criteria:
Major Criteria:
-
- Blood cultures positive for typical organisms (2 separate cultures).
- Echocardiogram positive for vegetation, abscess, or new partial dehiscence of prosthetic valve.
Minor Criteria:
-
- Predisposing heart condition or IVDU.
- Fever (>38°C).
- Vascular phenomena (Janeway lesions, arterial emboli, mycotic aneurysm).
- Immunologic phenomena (Osler nodes, Roth spots, glomerulonephritis).
- Microbiological evidence not meeting major criteria.
3. Exam Must-Knows (Clinical Pearls)
Clinical Core: Osler nodes are painful, raised red lesions on fingers/toes (immune-complex mediated). Janeway lesions are painless, flat erythematous macules on palms/soles (septic emboli).
- Roth Spots: Retinal hemorrhages with pale centers.
- Culture-Negative IE: Think HACEK group (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella), Coxiella burnetii, or Bartonella.
- Vegetations: Large, friable, destructive vegetations that can embolize to distant organs (brain, spleen, kidneys).