Pediatric Infective Endocarditis - Comprehensive Clinical Review

Overview & Epidemiology

• Annual incidence: 0.05 to 0.12 cases per 1,000 pediatric admissions (low, but significant morbidity)
• Mortality: 10-15% despite declining trends
• Major complications: septic emboli, valvular dysfunction, congestive heart failure

Risk Factors in Children

Pathogenesis

1. Damaged endocardium - from turbulent flow, jet lesions, prosthetic material, or pacemaker wires
2. Circulating bacteria - from bacteremia (dental procedures, GI/GU manipulation, skin infections, IV drug use, or trivial daily activities like tooth brushing)

Microbiology

Classification

Clinical Features

• Fever (most common) - unexplained or persistent fever is the hallmark
• Fatigue, weakness, arthralgias, myalgias, weight loss, rigors, diaphoresis (older children)
• Subtler presentations in infants
• In cyanotic CHD patients: pneumonia, new neurologic deficits, hematuria, or skin rashes should trigger IE suspicion

• Fever + tachycardia + new or changing cardiac murmur (present in 90% of left-sided lesions)
• Splinter hemorrhages - linear subungual hemorrhages in nail beds
• Janeway lesions - painless erythematous macules on palms/soles (septic emboli)
• Osler nodes - tender subcutaneous nodules on fingers (immune complex deposition)
• Roth spots - retinal hemorrhages with pale centers
• Splenomegaly (subacute disease)
• CNS focal neurologic deficits (cerebral emboli)
• Rales/decreased breath sounds (septic pulmonary emboli - right-sided IE)

Echocardiographic Findings

Diagnosis

Modified Duke Criteria

Major Criteria:

1. Positive blood cultures:
   • 2 positive cultures for a typical IE organism, OR
   • Persistently positive cultures (same organism over 12 h, or 3+ cultures with ≥1 h between first and last), OR
   • Single positive culture for Coxiella burnetii
2. Endocardial involvement on echocardiography:
   • Vegetation, abscess, new valvular regurgitation, or prosthetic valve dehiscence

Minor Criteria:

1. Fever ≥38°C (100.4°F)
2. Predisposing heart condition or injection drug use
3. Vascular phenomena (emboli, mycotic aneurysm, intracranial hemorrhage)
4. Immunologic phenomena (elevated RF, immune complex GN, Osler nodes, Roth spots)
5. Positive blood culture not meeting major criterion

Classification:

• Definite IE: 2 major criteria, OR 1 major + 3 minor criteria, OR 5 minor criteria
• Possible IE: 1 major + 1 minor criterion, OR 3 minor criteria

Investigations:

• Blood cultures: 3 separate samples in first 24 hours; 1-3 mL (infants), 3-5 mL (toddlers/preschool), 10 mL (school-age/adolescents). Repeat at 48 h if negative.
• CBC: Anemia of chronic disease; leukocytosis may be absent
• ESR/CRP: Usually elevated (mean ESR ~55 mm/h)
• Rheumatoid factor: Positive in subacute/chronic disease
• Urinalysis: Proteinuria and microscopic hematuria in ~50% (immune complex GN)
• TTE: More sensitive in children than adults (better acoustic windows); reveals vegetations, abscess, valvular regurgitation
• TEE: Better sensitivity than TTE for prosthetic valves and perivalvular extension

Treatment

Empiric Antibiotic Therapy (ED initiation after cultures):

• Vancomycin 15 mg/kg IV q6h (max 2 g per dose) - for MRSA coverage
• + Gentamicin 5-7.5 mg/kg IV q24h - synergistic bactericidal effect

• Penicillin G 50,000-100,000 units/kg IV q6h, OR
• Ceftriaxone 100 mg/kg IV daily

• Prolonged parenteral antibiotic course (4-6 weeks typically required for complete eradication)
• Hospitalization mandatory
• Pediatric cardiology consultation indicated
• Pediatric cardiac surgery consultation for hemodynamic instability

Surgical Indications:

• Uncontrolled infection despite adequate antibiotics
• Heart failure from valvular dysfunction
• Large vegetations at high embolic risk
• Perivalvular abscess/extension

Prophylaxis

• Prosthetic cardiac valve or prosthetic material used for valve repair
• Previous IE
• Unrepaired cyanotic CHD (including palliative shunts/conduits)
• Completely repaired CHD with prosthetic material within the first 6 months after procedure
• Repaired CHD with residual defect at/adjacent to prosthetic patch or device
• Cardiac transplantation with subsequent valvulopathy

• Oral: Amoxicillin 50 mg/kg PO
• Parenteral: Ampicillin 50 mg/kg IM/IV
• Penicillin-allergic:
  • Cephalexin 50 mg/kg PO, OR
  • Clindamycin 20 mg/kg PO/IV, OR
  • Azithromycin 15 mg/kg PO

Complications

Recent Evidence Update

Key Pediatric-Specific Pearls

1. 90% have structural heart disease - always evaluate for underlying CHD
2. Neonates are special - gram-negatives and Candida are important pathogens; often linked to central venous catheters
3. Subacute presentations mimic common illness - maintain suspicion for persistent unexplained fever in any child with CHD
4. TTE is preferred initially in children (better acoustic windows than adults)
5. HACEK organisms are characteristic of IE in children and adolescents with normal dental hygiene and CHD
6. Right-sided IE (tricuspid) is associated with central venous catheter use and presents with septic pulmonary emboli
7. Outcome depends heavily on the infecting organism and speed of diagnosis and treatment