Diagnostic Criteria and Treatment Guidelines for Infective Endocarditis

Diagnostic Criteria

The European Society of Cardiology recommends using the modified Duke criteria with the 2015 ESC updates for the diagnosis of infective endocarditis, which include blood culture findings, echocardiographic evidence, and clinical manifestations 1, 2
Microorganisms demonstrated by culture or histological examination of a vegetation, embolized vegetation, or intracardiac abscess specimen is a major criterion for the diagnosis of infective endocarditis 1
Pathological lesions showing active endocarditis (vegetation or intracardiac abscess) by histological examination is a major criterion for the diagnosis of infective endocarditis 2
The diagnosis of definite infective endocarditis can be made with 2 major criteria, or 1 major criterion and 3 minor criteria, or 5 minor criteria 1, 2, 3

Blood cultures positive for typical microorganisms such as viridans streptococci, Streptococcus gallolyticus, HACEK group, Staphylococcus aureus, or community-acquired enterococci without primary focus is a major criterion for the diagnosis of infective endocarditis 2, 4
Imaging positive for infective endocarditis, such as echocardiogram showing vegetation, abscess, pseudoaneurysm, intracardiac perforation, new partial dehiscence of prosthetic valve, or new valvular regurgitation, is a major criterion for the diagnosis of infective endocarditis 2, 5

Predisposition to infective endocarditis, such as predisposing heart condition or injection drug use, is a minor criterion for the diagnosis of infective endocarditis 3, 4
Fever, defined as temperature ≥38°C, is a minor criterion for the diagnosis of infective endocarditis 3, 4
Vascular phenomena, such as major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial hemorrhages, conjunctival hemorrhages, Janeway lesions, is a minor criterion for the diagnosis of infective endocarditis 3, 4

The American College of Cardiology recommends that treatment of infective endocarditis should be guided by the identified causative organism, with specific antimicrobial regimens for different types of organisms 8
For streptococcal infective endocarditis, the recommended treatment is aqueous crystalline penicillin G sodium or ceftriaxone for 4 weeks 9
For staphylococcal infective endocarditis, the recommended treatment is anti-staphylococcal penicillin or cefazolin for methicillin-sensitive S. aureus, and vancomycin for methicillin-resistant strains 8
Surgical intervention should be considered in cases with heart failure due to valve dysfunction, uncontrolled infection, prevention of embolic events, or prosthetic valve endocarditis 8

Early diagnosis is crucial for improved outcomes in infective endocarditis, with mortality rates remaining high despite advances in treatment 8
Echocardiography plays a central role in the diagnosis of infective endocarditis, with transesophageal echocardiography recommended when transthoracic echocardiography is negative but clinical suspicion remains high 8, 9
The sensitivity of the modified Duke criteria is approximately 80% when evaluated at the end of patient follow-up, but may be lower during early clinical assessment 2