Infective Endocarditis¶

Learning Objectives¶

Core Knowledge & Clinical Reasoning¶

Identify patients at highest risk for infective endocarditis based on underlying cardiac anatomy
Recognize the modified Duke criteria and apply them to classify cases as definite, possible, or rejected IE
Differentiate clinical presentations of acute vs subacute endocarditis
Analyze blood culture and imaging findings to establish the diagnosis
Evaluate echocardiographic findings to determine vegetation size, location, and complications

Management Decisions¶

Select appropriate empiric antibiotic regimens based on clinical presentation and suspected organisms
Determine the appropriate duration of therapy based on organism and valve involvement
Identify indications for urgent surgical intervention in pediatric IE
Formulate a monitoring plan for treatment response including repeat imaging

Communication & Counseling¶

Counsel families on the duration and intensity of treatment required
Discuss long-term implications including need for IE prophylaxis and surveillance
Explain the importance of dental health in IE prevention

Systems-Based Practice¶

Coordinate multidisciplinary care involving cardiology, infectious disease, and cardiac surgery
Recognize when to transfer to a center with pediatric cardiac surgery capabilities
Implement transition planning for outpatient parenteral antibiotic therapy (OPAT)

Epidemiology¶

Incidence¶

Pediatric IE: 0.34-0.64 per 100,000 children per year
Increasing incidence due to:
More CHD survivors
Increased device implantation
Central line use

Risk Factors (Highest to Lowest)¶

Risk Category	Conditions
Highest risk	Prosthetic valves, previous IE, unrepaired cyanotic CHD, conduits
High risk	Repaired CHD with residual defects, ACHD with valvulopathy
Moderate risk	Unrepaired ASD, VSD, PDA; mitral valve prolapse with regurgitation
Lower risk	Most repaired CHD >6 months post-op without residual

Microbiology¶

Organism	Frequency	Setting
Viridans streptococci	35-40%	Native valve, dental procedures
Staphylococcus aureus	25-35%	Acute, healthcare-associated, devices
HACEK organisms	5-10%	Culture-negative initially
Coagulase-negative staph	10-15%	Prosthetic valves, lines
Enterococcus	5-10%	GI/GU procedures
Culture-negative	5-15%	Prior antibiotics, fastidious organisms

Clinical Presentation¶

Acute Endocarditis¶

High fever, toxic appearance
Rapid progression
Usually S. aureus
May present with sepsis, stroke, or heart failure

Subacute Endocarditis¶

Low-grade fever, malaise
Weight loss, night sweats
Arthralgias, myalgias
Often viridans streptococci or enterococcus
Develops over weeks to months

Classic Findings¶

Finding	Description	Frequency
Fever	Most common symptom	80-90%
New/changed murmur	Especially regurgitant	30-50%
Splenomegaly	Subacute disease	20-40%
Petechiae	Conjunctivae, oral mucosa	10-30%
Splinter hemorrhages	Nail bed	5-15%
Janeway lesions	Painless palmar/plantar	5-10%
Osler nodes	Painful fingertip nodules	3-10%
Roth spots	Retinal hemorrhages	2-5%

Diagnosis¶

Modified Duke Criteria¶

Major Criteria:

Positive blood cultures
Typical organism from 2 separate cultures OR
Persistently positive cultures (>12 hours apart) OR
Single culture or serology for Coxiella burnetii
Evidence of endocardial involvement
Echocardiogram showing vegetation, abscess, or new dehiscence OR
New valvular regurgitation

Minor Criteria:

Predisposing heart condition or IVDU
Fever ≥38°C
Vascular phenomena (emboli, mycotic aneurysm, Janeway lesions)
Immunologic phenomena (Osler nodes, Roth spots, RF, glomerulonephritis)
Positive blood cultures not meeting major criteria

Definite IE¶

2 major criteria OR
1 major + 3 minor OR
5 minor criteria

Possible IE¶

1 major + 1 minor OR
3 minor criteria

Blood Cultures¶

Technique: - Draw 3 sets from separate sites - Before antibiotics whenever possible - No need to time with fever - Pediatric volumes: 1-3 mL per bottle

Interpretation: - Most will be positive within 48 hours - Hold cultures for 21 days if HACEK suspected - Consider serologies if culture-negative: Bartonella, Coxiella, Brucella

Echocardiography¶

TTE First: - Adequate for most pediatric cases - Better windows in children than adults

TEE Indications: - Poor TTE windows - Prosthetic valve involvement - Suspected paravalvular abscess - Pre-operative evaluation

Key Findings:

Finding	Significance
Vegetation	Oscillating mass on valve
Abscess	Echo-lucent area, high surgical risk
Pseudoaneurysm	Contained rupture
Fistula	Abnormal flow between chambers
New regurgitation	Valve destruction
Dehiscence	Prosthetic valve

Vegetation Size Matters: - >10 mm: Higher embolic risk - >15 mm: Very high risk, consider surgery

Treatment¶

Empiric Therapy¶

Native Valve:

Vancomycin + Gentamicin
(Covers MRSA and streptococci pending cultures)

Prosthetic Valve:

Vancomycin + Gentamicin + Rifampin
(Must cover staph, including coag-negative)

Organism-Specific Therapy¶

Organism	Regimen	Duration
Viridans strep (MIC <0.12)	Penicillin G or Ceftriaxone	4 weeks
Viridans strep (MIC 0.12-0.5)	Penicillin + Gentamicin	4-6 weeks
MSSA	Nafcillin or Oxacillin	6 weeks
MRSA	Vancomycin	6 weeks
Enterococcus	Ampicillin + Gentamicin	4-6 weeks
HACEK	Ceftriaxone	4 weeks

Prosthetic Valve IE¶

Extend all durations to 6 weeks minimum
Add rifampin for staphylococcal infection
Lower threshold for surgery

Aminoglycoside Synergy¶

Gentamicin 3 mg/kg/day divided q8h
Monitor levels and renal function
Duration: 2 weeks for synergy (not full course)

Complications¶

Cardiac¶

Complication	Frequency	Management
Heart failure	30-40%	Medical therapy, often needs surgery
Abscess	10-20%	Almost always requires surgery
Heart block	5-10%	Abscess near conduction system
Pericarditis	5-10%	May be purulent

Embolic¶

Site	Presentation
CNS	Stroke, mycotic aneurysm, meningitis
Pulmonary	Right-sided IE (septic emboli)
Splenic	Abdominal pain, abscess
Renal	Infarct, abscess, glomerulonephritis
Bone	Osteomyelitis

CNS Complications¶

Stroke in 20-40% of IE
Mycotic aneurysm: SAH risk
Timing of surgery after stroke:
Hemorrhagic: Delay 4 weeks
Ischemic only: May operate within 2 weeks if needed

Surgical Indications¶

Urgent (Within Days)¶

Indication	Notes
Heart failure from valve dysfunction	Aortic or mitral regurgitation
Fungal endocarditis	Medical therapy rarely curative
Annular or aortic abscess	Requires debridement
Heart block (new)	Suggests abscess
Persistent sepsis >5-7 days	Despite appropriate antibiotics

Relative Indications¶

Large vegetation (>10 mm) with embolic event
Very large vegetation (>15 mm) even without emboli
Prosthetic valve endocarditis with S. aureus
Recurrent emboli despite therapy
Relapse after appropriate therapy

Right-Sided IE¶

Generally more conservative approach
Surgery for:
Persistent sepsis
Large vegetations with recurrent pulmonary emboli
Tricuspid valve destruction

Special Populations¶

Neonates¶

Often healthcare-associated
Central line-related
S. aureus, coagulase-negative staph, Candida
High mortality

Post-Cardiac Surgery¶

Early (<60 days): Nosocomial organisms
Late: Community organisms
Prosthetic material increases risk

CHD Patients¶

Lesion	Typical Involvement
VSD	Tricuspid valve (jet lesion)
PDA	Pulmonary end
Coarctation	Bicuspid aortic valve
Single ventricle	Any valve, conduit

Monitoring Response¶

During Treatment¶

Daily exam for first week
Temperature curve (should defervesce within 1 week)
Repeat blood cultures until negative (usually 48-72 hours)
Weekly labs: CRP, renal function, CBC

Repeat Echocardiography¶

Baseline at diagnosis
1-2 weeks into therapy (or sooner if clinical change)
End of therapy
Vegetation may persist after cure

Outpatient Completion¶

OPAT for stable patients after initial inpatient phase
Requirements:
Clinically stable, afebrile
Reliable IV access (PICC)
Family education
Close follow-up

Prevention¶

See: Topic 07 - IE Prophylaxis

High-Risk Conditions Requiring Prophylaxis¶

Prosthetic valves
Previous IE
Unrepaired cyanotic CHD
Repaired CHD with residual defects
Cardiac transplant with valvulopathy

Procedures Requiring Prophylaxis¶

Dental procedures involving gingival tissue or periapical region
Respiratory procedures involving incision of mucosa

Dental Health¶

Good dental hygiene reduces bacteremia
Regular dental care essential
Address dental infections promptly

Long-Term Outcomes¶

Survival¶

In-hospital mortality: 5-15% (higher with prosthetic, S. aureus)
1-year mortality: 15-25%
Recurrence: 5-10%

Follow-Up¶

Cardiology surveillance for valve function
IE prophylaxis for life
Dental care optimization
Education on seeking care for fever

Key Teaching Points¶

Fever + predisposing cardiac lesion = think IE until proven otherwise
Blood cultures before antibiotics - 3 sets from separate sites
S. aureus causes acute, aggressive disease; streptococci cause subacute
Vegetation >10 mm increases embolic risk - discuss surgery
Duke criteria help classify but clinical judgment essential
6 weeks minimum for prosthetic valve IE
Surgery saves lives - don't delay when indicated
Right-sided IE is more forgiving - can often treat medically
Culture-negative IE - prior antibiotics, HACEK, or unusual organisms
Dental health is the best prevention

Key Guidelines¶

2015 AHA Scientific Statement: Infective Endocarditis in Childhood - Update Circulation. 2015;132(15):1487-1515 PMID: 26373317

2023 ESC Guidelines for the Management of Endocarditis Eur Heart J. 2023;44(39):3948-4042 PMID: 37622657

Board Pearls¶

Pearl: Modified Duke Criteria - 2 major OR 1 major + 3 minor OR 5 minor = definite IE

Major criteria: (1) Positive blood cultures with typical organism, (2) Echo evidence of vegetation/abscess/new regurgitation.

Pearl: Prosthetic valve + S. aureus = high mortality, low threshold for surgery

These patients have aggressive disease. Surgical consultation should occur early, even before completing antibiotics.

Pearl: 3 blood cultures from 3 separate sites BEFORE antibiotics

This is the single most important diagnostic test. Don't let anyone give antibiotics until cultures are drawn (unless critically ill).

References¶

Baltimore RS, et al. Infective Endocarditis in Childhood: 2015 Update - A Scientific Statement From the American Heart Association. Circulation. 2015.
Baddour LM, et al. Infective Endocarditis in Adults: Diagnosis, Antimicrobial Therapy, and Management of Complications. Circulation. 2015.
Habib G, et al. 2015 ESC Guidelines for the Management of Infective Endocarditis. Eur Heart J. 2015.
Day MD, et al. Characteristics of Children Hospitalized With Infective Endocarditis. Circulation. 2009.