Diagnostic Criteria for Pediatric Infective Endocarditis

Major Criteria

• The American Heart Association recommends that typical microorganisms consistent with IE from ≥2 blood cultures, such as Viridans streptococci, Streptococcus bovis, or HACEK group, be considered a major criterion for the diagnosis of pediatric infective endocarditis 1
• Community-acquired Staphylococcus aureus or enterococci (in the absence of a primary focus) are also considered major criteria for the diagnosis of pediatric infective endocarditis 1, 3
• Persistently positive blood cultures defined as ≥2 positive cultures of blood samples drawn >12 hours apart, or all of 3 or a majority of ≥4 blood cultures, irrespective of timing, are considered a major criterion for the diagnosis of pediatric infective endocarditis 1, 4
• A single positive blood culture for Coxiella burnetii or anti-phase I IgG antibody titer >1:800 is considered a major criterion for the diagnosis of pediatric infective endocarditis 1, 5
• Positive echocardiogram (TEE recommended for prosthetic valves or complicated IE; TTE as first test in other patients) showing oscillating intracardiac mass on valve or supporting structures, in the path of regurgitant jets, or on implanted material without alternative explanation, is considered a major criterion for the diagnosis of pediatric infective endocarditis 1
• Abscess, new partial dehiscence of prosthetic valve, or new valvular regurgitation (worsening or changing of preexisting murmur not sufficient) are also considered major criteria for the diagnosis of pediatric infective endocarditis 1, 4

Minor Criteria

• Predisposition, such as predisposing heart condition or intravenous drug use, is considered a minor criterion for the diagnosis of pediatric infective endocarditis 1, 4
• Fever, defined as temperature ≥38.0°C, is considered a minor criterion for the diagnosis of pediatric infective endocarditis 1
• Vascular phenomena, such as major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial hemorrhage, conjunctival hemorrhages, and Janeway lesions, are considered minor criteria for the diagnosis of pediatric infective endocarditis 1, 4
• Immunologic phenomena, such as glomerulonephritis, Osler nodes, Roth's spots, and rheumatoid factor, are considered minor criteria for the diagnosis of pediatric infective endocarditis 1, 4
• Microbiological evidence, such as positive blood culture but does not meet a major criterion or serological evidence of active infection with organism consistent with IE, is considered a minor criterion for the diagnosis of pediatric infective endocarditis 1, 4

Diagnostic Classification

• Definite IE is diagnosed when pathological criteria, such as microorganisms demonstrated by culture/histology in vegetation, embolized vegetation, or intracardiac abscess, or clinical criteria, such as 2 major criteria, or 1 major criterion and 3 minor criteria, or 5 minor criteria, are met 2, 6
• Possible IE is diagnosed when 1 major criterion and 1 minor criterion, or 3 minor criteria are met 2, 6

Diagnostic Approach

• The American Heart Association recommends drawing blood cultures for patients with fever of unexplained origin and a pathological heart murmur, history of heart disease, or previous endocarditis 1, 2
• Obtaining 3 blood cultures by separate venipunctures on the first day, and if no growth by second day of incubation, obtaining 2-3 more, is recommended for the diagnosis of pediatric infective endocarditis 1
• For severely ill and unstable patients, performing 3 separate venipunctures over 1-2 hours and initiating empirical antibiotic therapy is recommended 1
• Withholding antibiotics for ≥48 hours in non-acutely ill patients with negative cultures to improve diagnostic yield is recommended 1

Common Pitfalls and Caveats

• Blood culture remains the cornerstone of diagnosis, and failure to obtain adequate cultures before antibiotic administration is a major cause of culture-negative endocarditis 7
• The presence of a central venous catheter may prolong bacteremia, potentially requiring catheter removal before diagnostic criteria are met 8
• S. aureus bacteremia should be considered a major criterion regardless of whether the infection is nosocomial or community-acquired 3, 8
• 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