Week 4: Infective Endocarditis

Question 1

Describe pathogenesis of infective endocarditis.

Answer 1

• organisms get to valve through bloodstream
• organisms adhere to damaged valve surfaces
• bacterial growth in protective sheath of fibrin and platelets with growth of the vegetation
• any valve can be infected

Question 2

What are the infectious causes of endocarditis?

Answer 2

1. Staph aureus (37%) most common
   - often hospital acquired
   - assoc. with intravascular device
   - common in IV drug users, usually tricuspid
   - complications: myocardial abscesses, valve ring abscesses, purulent pericarditis, peripheral abscesses
   - mortality is >50% in >50yo w/Rx
2. Viridans streptococci (19%) -gram+ alpha hemolytic, live in oral cavity
   - spread from mouth abscesses, gingivitis, oral lesions
3. Group D S. gallolyticus (bovis)
   - primarily in GI tract, assoc. with colon cancer
4. Enterococci
5. Nutritionally deficient streptococci (Abiotrophia, Granulicatella)
   - need Vit B6 to grow, diff. to isolate, don’t grow on blood agar
6. HACEK group
7. other uncommon ones: gram - bacilli, anaerobes, fungi, Coxiella, Brucella
8. culture negative: 3 neg. blood cultures: fungi, Ricketsiae, Chlamydia e.g.

Question 3

What are the HACEK group of organisms?

Answer 3

-group of gram negative coccobacilli, part of normal oral flora
Haemophilus species
Actinobacillus actinomycetemcomitans
Cardiobacterium hominis
Eikenella corrodens
Kingella spp

Question 4

What is the most common organism for prosthetic valve endocarditis?

Answer 4

Gram neg. staphylococci such as S. epidermitis

Question 5

What are physical findings in infective endocarditis?

Answer 5

1. fever
2. changing heart murmur
3. Peripheral stigmata
   - splinter hemorrhages
   - petechiae
   - Osler nodes: tender nodes on pulp of digits
   - Janeway lesions: painless macules on palms and soles
   - Roth spots: retinal hemorrhage w/ clear center

Question 6

What are the most complications of infective endocarditis?

Answer 6

1. CHF 50-60%
2. Peripheral emboli 20-25%
3. glomerulonephritis 15-25%
4. stroke 5-15%
5. mycotic aneurysm 15%

Question 7

How do you diagnose infective endocarditis?

Answer 7

Duke criteria: 2 major or 1 major/3minor or 5 minor for definite IE
MAJOR
-2 separate blood cultures positive
-evidence of endocardial involvement on echocardiogram
MINOR
-predisposing lesion or IV drug use
-fever>38 C
-Peripheral stigmata signs
-glomerulonephritis, rheumatoid factor
-positive blood cultures not meeting major criterion
-serologic evidence of active infection with organism that causes IE
-Echo consistent with endocarditis but not meeting major criterion

Question 8

Describe treatment for infective endocarditis.

Answer 8

• bactericidal (not bacteriostatic) antibiotic active against organism identified
• repeat blood cultures until shows no growth
• long term IV antibiotic Rx

Question 9

What are indications for surgery for IE?

Answer 9

-refractory CHF
->1 serious systemic embolic episode
-uncontrolled bacteremia> 7days
-intracardial abscess
-fever> 7 days
-fungal endocarditis
Above is occurring despite antimicrobial Rx
ONLY for certain indications prophylaxis is helpful for preventing IE