Infective Endocarditis

Question 1

Infective Endocarditis

Answer 1

•Infective endocarditis (IE) refers to infection of the endocardial surface of the heart. The cardiac valves are involved in the great majority of cases, but infection may also occur on the mural surface or on septal defects. IE has been extensively studied because its wide variety of manifestations can mimic other diseases, and because of its complex pathophysiology

Question 2

Pathophysiology of IE

Answer 2

1. Endothelial damage
2. Bacteremia (septicemia)
3. Formation of infected vegetation
4. Inflammation

Question 3

Endothelial Damage

Answer 3

• Aging valves
• Previously damaged valves (rheumatic fever or previous IE)
• Bicuspid aortic valve (1% of population)
• Prosthetic valves
• Turbulence (shunts, regurgitation)
• Mechanical trauma (catheter)

Question 4

Answer 4

Question 5

Answer 5

Question 6

Inflammation

Answer 6

• Presence of intravascular bacteria leads to immune system activation
• Complement activation
• Production of autoantibodies: rheumatoid factor, antinuclear antibodies
• Immune complex formation

Question 7

Clinical Manifestations are a Consequence of:

Answer 7

• Bacteremia
• Valvular vegetations
• Embolization
• Immune complex deposition
• Nonspecific immune stimulation

Question 8

Signs and Symptoms

Answer 8

Question 9

Fever of Unknown Origin (FUO)

Answer 9

1. Illness of >3 weeks duration
2. Fever greater than 101 F, (38.3 C) on several occasions
3. No diagnosis despite one week of intensive evaluation

Question 10

Cardiovascular Manifestations

Answer 10

Question 11

A consequence of perivalvular abscess

Answer 11

Question 12

Consequences of septic emboli Right sided

Answer 12

Question 13

Consequences of septic emboli Left sided

Answer 13

Question 14

Immune complexes in IE

Answer 14

• Nephritis
• Arthritis
• Vasculitis

Question 15

Subcutaneous Nodules (Osler’s nodes)

Answer 15

Question 16

Consequences of Bacteremia

Answer 16

Question 17

Immune System Activation

Answer 17

• Circulating rheumatoid factor
• Hyperglobulinemia
• Splenomegaly
• Thrombocytopenia

Question 18

Diagnosis

Answer 18

Question 19

Duke Clinical Criteria: Major

Answer 19

Question 20

Duke Clinical Criteria: Minor

Answer 20

Question 21

Treatment of IE: Principles

Answer 21

• Bacteria in vegetations are relatively protected from antibiotic penetration AND immune system action
• High concentrations of bactericidal antibiotics and long duration of therapy are used
• Surgery may be needed for large vegetations or valvular damage

Question 22

Antibiotic selection

Answer 22

• Cell wall active agents for Gram positive organisms
• Aminoglycoside or beta-lactam synergy especially for enterococci prosthetic valves

Question 23

Answer 23

Question 24

Prevention of IE with Antibiotics?

Answer 24

Principles:

• IE is uncommon but life threatening
• Certain cardiac conditions predispose to IE
• Bacteremia with IE-causing organisms occurs during certain invasive procedures
• Occasional cases of IE following procedures have been reported

Question 25

Can antibiotic prophylaxis prior to invasive procedures prevent IE?

Answer 25

• Bacteremia occurs at least as commonly from daily activities as from procedures
• It is difficult to show that prophylaxis actually prevents IE
• On a population level, risk of antibiotic adverse effects may be greater than benefit of prophylaxis
• Cost effectiveness analyses are not favorable

Question 26

IE Prevention

Answer 26

Antibiotic recommendations

• Amoxicillin 2 grams single dose
• PCN allergy: cephalexin 2 grams
• Anaphylactic PCN allergy: clindamycin 600 mg or azithromycin or clarithromycin 500 mg