Infective Endocarditis Flashcards
What is infective endocarditis?
Infection of endocardium - valves, septal defects, mural endocardium
95% involves left heart - Mitral and Aortic valve
IVDU more frequently right heart
Classification of IE
- Native valve endocarditis
- SA: affects all valves equally
- S. viridans: affects abnormal valves
- Presence of insults: RHD, congenital, MVP, degenerative valve - Prosthetic valve endocarditis
- Early (within 60 days of replacement)
- Late (similar to native endocarditis) - Right sided endocarditis (IVDU)
- Usually Tricuspid valve, less aortic valve
- SA, MRSA, fungi, strep, GNB
Osler Nodes and Janeway Lesions
Osler Nodes
- tender papules
- pulps of fingers and toes, thenar and hypothenar eminences
-> deposition of immune complexes
Janeway lesions
- non tender hemorrhage
- palms and soles
-> septic microembolisms
Duke Criteria
2 Major
1 Major 3 Minor
5 Minor
Major:
1. positive blood culture x2 or persistent
2. positive echocardiogram or new valvular regurgitation
- Vegetations, abscess, valve perf, dehiscence
Minor:
1. Predisposing: heart condition, IVDU
2. Fever > 38 degree
3. Vascular phenomenon: major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, ICH, conjunctival hemorrhage, Janeway lesions
4. Immunologic phenomenon: GN, Osler nodes, Roth spot (RH), rheumatoid factor
5. Positive blood culture but not meeting major criteria
6. Positive echocardiogram but not meeting major criteria
Antibiotics prophylaxis for IE before surgery
Given for dental, respiratory, gastrointestinal and genitourinary procedures
Amoxicillin 2g, 1 hour before procedure or
Clindamycin 600mg
Azithromycin 500mg
Clarithromycin 500mg
What are the typical organisms involved in IE?
Strep and staph
- Streptococcus viridans
- Streptococcus bovis (a/w colorectal cancer)
- Enterococci
- Staphylococcus aureus (a/w IVD users)
- Staphylococcus epidermidis (prosthetic valve)
HACEK
- Haemophilus
- Actinobacillus
- Cardiobacterium
- Eikenella
- Kingella
How do you investigate for IE?
- FBC: anaemia (HA), leukocytosis with neutrophilia
- ESR, CRP
- Blood culture
- TTE
- CXR
- ECG
How do you treat infective endocarditis?
- General measures - oxygen, supportive
- Antibiotics tailored to culture and sensitivity
- Surgery if indicated -> see indications for surgery
What are the indications for surgery in IE?
- Heart failure
- Failure of medical therapy
- Persistent fever, inflammatory syndrome after 1 week of appropriate and adequate anbitiotics
- Mobile vegetation > 10mm with 1 major embolism
- Mobile vegetation > 15mm - Valvular complications: abscess, obstruction, rupture into pericardium, septal formation, fistula
- Fungal endocarditis
- Prosthetic valve, especially unstable or early, caused by SA
What is the prognosis of IE?
Dependent on undelying cause
- 30% staphylococci
- 14% enterococcus
- 50% if prosthetic valve
- MVP - 5 year death rate 22-33%
Survivability >70% with endogenous infection, 50% with prosthetic valve infection
What is non-infective endocarditis?
(Libman-Sacks endocarditis)
Sterile vegetation in SLE or ALPS, not along lines of valve closure
Usually postmortem finding
(Rare due to advent of steroid therapy)
Pathogenesis of IE
Predisposing
- Blood flow derangement from underlying abnormality
- Increased trauma to endocardial surface
- Formation of sterile platelet-fibrin deposits
Precipitating
- Seeding of organisms during bacteraemia
> IVD, dental or surgical procedure, occult source (brushing teeth), bacteria clumps from agglutinating antibodies
What are the complications of IE?
- Valve destruction, obstruction or regurgitation
- Heart failure
- Infection extension -> ring abscess
- Conduction defect
- Thromboembolism - brain, kidney, lungs, spleen, bowel
- Mycotic aneurysm
- Distal organ seeding - cerebral abscess
- Glomerulonephritis (deposition of immune complexes and complement activation)
