What are the diagnostic criteria for pediatric endocarditis?

Diagnostic Criteria for Pediatric Infective Endocarditis

The diagnosis of pediatric infective endocarditis is based on the Modified Duke Criteria, which includes major and minor criteria evaluating blood culture results, echocardiographic findings, and clinical manifestations. 1

Major Criteria

1. Positive Blood Culture for IE

• Typical microorganisms consistent with IE from ≥2 blood cultures:
  • Viridans streptococci, Streptococcus bovis, or HACEK group 1
  • Community-acquired Staphylococcus aureus or enterococci (in the absence of a primary focus) 1
• Persistently positive blood cultures defined as:
  • ≥2 positive cultures of blood samples drawn >12 hours apart 1
  • All of 3 or a majority of ≥4 blood cultures, irrespective of timing 1
  • Single positive blood culture for Coxiella burnetii or anti-phase I IgG antibody titer >1:800 1

2. Evidence of Endocardial Involvement

• Positive echocardiogram (TEE recommended for prosthetic valves or complicated IE; TTE as first test in other patients) showing: 1
  • Oscillating intracardiac mass on valve or supporting structures, in the path of regurgitant jets, or on implanted material without alternative explanation 1
  • Abscess 1
  • New partial dehiscence of prosthetic valve 1
• New valvular regurgitation (worsening or changing of preexisting murmur not sufficient) 1

Minor Criteria

• Predisposition: predisposing heart condition or intravenous drug use 1
• Fever: temperature ≥38.0°C 1
• Vascular phenomena: major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial hemorrhage, conjunctival hemorrhages, and Janeway lesions 1
• Immunologic phenomena: glomerulonephritis, Osler nodes, Roth's spots, and rheumatoid factor 1
• Microbiological evidence: positive blood culture but does not meet a major criterion or serological evidence of active infection with organism consistent with IE 1

Diagnostic Classification

• Definite IE: 1

  • Pathological criteria: microorganisms demonstrated by culture/histology in vegetation, embolized vegetation, or intracardiac abscess; OR pathological lesions with active endocarditis
  • Clinical criteria: 2 major criteria; OR 1 major criterion and 3 minor criteria; OR 5 minor criteria

• Possible IE: 1

  • 1 major criterion and 1 minor criterion; OR
  • 3 minor criteria

• Rejected IE: 1

  • Firm alternative diagnosis explaining evidence of IE; OR
  • Resolution of IE syndrome with antibiotic therapy for ≤4 days; OR
  • No pathological evidence of IE at surgery or autopsy with antibiotic therapy for ≤4 days; OR
  • Does not meet criteria for possible IE

Diagnostic Approach

Blood Culture Recommendations

• Draw blood cultures for patients with fever of unexplained origin and a pathological heart murmur, history of heart disease, or previous endocarditis 1
• Obtain 3 blood cultures by separate venipunctures on the first day; if no growth by second day of incubation, obtain 2-3 more 1
• For severely ill and unstable patients, perform 3 separate venipunctures over 1-2 hours and initiate empirical antibiotic therapy 1
• Consider withholding antibiotics for ≥48 hours in non-acutely ill patients with negative cultures to improve diagnostic yield 1

Special Considerations in Pediatric Patients

• The modified Duke criteria have demonstrated higher sensitivity (88%) compared to the original Duke criteria (81%) and von Reyn criteria (63%) in diagnosing pediatric IE 2
• Central venous catheters are a significant risk factor for IE in children without underlying heart disease 3
• S. aureus is the most common pathogen in children with IE without underlying heart disease, while viridans streptococci are more common in those with congenital heart disease 1, 3
• Echocardiographic evidence is critical in pediatric diagnosis, with initial echocardiogram suggesting IE in up to 95% of cases 2

Common Pitfalls and Caveats

• Blood culture remains the cornerstone of diagnosis - failure to obtain adequate cultures before antibiotic administration is a major cause of culture-negative endocarditis 1
• Some cases (approximately 12%) may still be classified as "possible IE" despite having major echocardiographic findings if blood cultures remain negative 2
• The presence of a central venous catheter may prolong bacteremia, potentially requiring catheter removal before diagnostic criteria are met 1
• S. aureus bacteremia should be considered a major criterion regardless of whether the infection is nosocomial or community-acquired, which differs from earlier criteria 1
• For suspected culture-negative IE, consultation with microbiology laboratory director or pediatric infectious disease specialist is recommended for guidance on molecular pathogen identification and serological testing 1