Infective Endocarditis

Question 1

Define infective endocarditis (IE).

Answer 1

Infective endocarditis is an infection of the endocardial surface of the heart, usually involving the heart valves, caused by bacteria or fungi. It results in vegetation formation composed of fibrin, platelets, microorganisms, and inflammatory cells.

Question 2

Describe the epidemiology of infective endocarditis in children.

Answer 2

Uncommon in children but serious. Occurs mainly in those with congenital heart disease (CHD) or rheumatic heart disease (RHD). Incidence: 0.3–0.8 per 1,000 children with CHD per year. Mortality ~10–20%.

Question 3

List common causative organisms of infective endocarditis.

Answer 3

• Streptococcus viridans – common after dental procedures
• Staphylococcus aureus – most common overall, especially in acute IE
• Coagulase-negative staphylococci – prosthetic valves
• Enterococci, HACEK group, fungi (Candida, Aspergillus) – rare.

Question 4

What are major predisposing factors for infective endocarditis?

Answer 4

1. Congenital heart disease (VSD, PDA, TOF)
2. Rheumatic valvular disease
3. Indwelling catheters or prosthetic valves
4. Immunosuppression
5. Poor dental hygiene or dental procedures.

Question 5

Which cardiac lesions carry the highest risk of IE?

Answer 5

High-risk lesions: prosthetic valves, unrepaired cyanotic CHD, previous IE, repaired CHD with prosthetic material within 6 months, residual defects at prosthetic patch site.

Question 6

Describe the pathogenesis of infective endocarditis.

Answer 6

Endothelial damage → platelet-fibrin thrombus (nonbacterial thrombotic endocarditis) → transient bacteremia → colonization of thrombus → vegetation formation. Vegetations cause valvular destruction, embolization, and immune complex deposition.

Question 7

List general clinical features of infective endocarditis.

Answer 7

Fever, malaise, weight loss, anemia, new or changing murmur, splenomegaly, petechiae, clubbing. Mnemonic: ‘FAMeS PC’ = Fever, Anemia, Murmur, Splenomegaly, Petechiae, Clubbing.

Question 8

List classic peripheral signs of infective endocarditis.

Answer 8

• Osler nodes – tender nodules on fingers/toes
• Janeway lesions – non-tender macules on palms/soles
• Roth spots – retinal hemorrhages with pale centers
• Splinter hemorrhages – nail beds.

Question 9

Describe clinical presentation in neonates and infants.

Answer 9

Often nonspecific: poor feeding, irritability, respiratory distress, sepsis unresponsive to antibiotics. Murmur may be absent early. S. aureus and Candida are common causative organisms.

Question 10

List complications of infective endocarditis.

Answer 10

1. Heart failure (valvular destruction)
2. Embolic events (brain, kidneys, spleen)
3. Glomerulonephritis (immune complex deposition)
4. Mycotic aneurysm
5. Conduction abnormalities
6. Death.

Question 11

What are the Modified Duke’s criteria for diagnosing infective endocarditis?

Answer 11

Major criteria:
1. Positive blood cultures with typical organisms.
2. Evidence of endocardial involvement (echo showing vegetation, abscess, or new regurgitation).

Minor criteria:
1. Predisposing condition
2. Fever ≥38°C
3. Vascular phenomena (emboli, Janeway lesions)
4. Immunologic phenomena (Osler nodes, Roth spots, GN)
5. Positive but non-typical culture or echo.
Diagnosis: Definite = 2 major OR 1 major + 3 minor OR 5 minor.

Question 12

List key investigations for suspected infective endocarditis.

Answer 12

• Blood cultures (≥3 sets before antibiotics)
• CBC: anemia, leukocytosis
• ESR, CRP: elevated
• Urinalysis: microscopic hematuria, proteinuria
• Echocardiography: vegetation, abscess, new regurgitation
• CXR: cardiomegaly, pulmonary congestion.

Question 13

What is the role of echocardiography in IE?

Answer 13

Essential for diagnosis. Transthoracic (TTE) or transesophageal (TEE) shows vegetations, abscesses, prosthetic valve dehiscence, and regurgitant lesions. TEE is more sensitive (90–100%). Repeat if clinical suspicion remains despite negative result.

Question 14

Outline general management principles for infective endocarditis.

Answer 14

1. Hospital admission
2. Obtain blood cultures before starting antibiotics
3. Start empiric IV antibiotics → modify based on culture results
4. Manage heart failure and complications
5. Prolonged IV therapy (4–6 weeks)
6. Surgical intervention when indicated.

Question 15

List empiric antibiotic regimens for infective endocarditis (native valve).

Answer 15

Empiric therapy (covering Streptococcus, Staphylococcus, Enterococcus):
• Ampicillin (or Penicillin G) + Gentamicin.
If MRSA suspected: add Vancomycin.
Duration: 4–6 weeks.
Adjust according to sensitivity.

Question 16

What are antibiotic regimens for prosthetic valve or healthcare-associated IE?

Answer 16

• Vancomycin + Gentamicin + Rifampicin for 6 weeks.
Covers MRSA and coagulase-negative staphylococci. Rifampicin added for prosthetic valve penetration.

Question 17

State indications for surgical treatment in IE.

Answer 17

1. Refractory heart failure
2. Uncontrolled infection (abscess, persistent bacteremia)
3. Large vegetations (>10 mm) with embolic risk
4. Prosthetic valve endocarditis
5. Fungal endocarditis.

Question 18

Who should receive antibiotic prophylaxis for IE?

Answer 18

High-risk patients:
• Previous IE
• Prosthetic cardiac valves/material
• Unrepaired cyanotic CHD
• Repaired CHD within 6 months or with residual defects.
• Cardiac transplant with valvulopathy.

Question 19

What procedures require antibiotic prophylaxis in high-risk patients?

Answer 19

1. Dental procedures involving gingival manipulation
2. Tonsillectomy/adenoidectomy
3. Respiratory mucosa incision (e.g., bronchoscopy with biopsy)
4. Procedures on infected skin or musculoskeletal tissue.
   Not needed for routine GI/GU procedures.

Question 20

Outline standard prophylactic antibiotic regimen for dental procedures.

Answer 20

Amoxicillin 50 mg/kg (max 2 g) orally, 30–60 minutes before procedure.
If allergic to penicillin: Clindamycin 20 mg/kg (max 600 mg).

Question 21

List key preventive strategies for infective endocarditis.

Answer 21

• Maintain good oral hygiene
• Prompt treatment of infections
• Regular follow-up for CHD/RHD patients
• Educate caregivers on recognizing fever in at-risk children.