Diagnosis is confirmed using:

• Positive microbiological cultures
• Histopathology
• Imaging findings
  
  
• Duke-ISCVID diagnostic criteria:
  
  

  Category	Criteria	Key Findings
  Pathological Criteria	Definitive pathological evidence	Identification of pathogens or characteristic histological features of active infective endocarditis in tissue or implanted cardiac material.
  Major Clinical Criteria	Microbiological evidence	Typical IE pathogens from ≥2 blood culture sets, or specific microbiological evidence (e.g., Coxiella burnetii, Bartonella spp., Tropheryma whipplei).
  	Imaging evidence	Echocardiography or cardiac CT showing characteristic IE findings (e.g., vegetations, abscess, new valvular regurgitation); FDG-PET/CT suggestive of IE in selected patients; direct surgical evidence.
  Minor Clinical Criteria	Predisposing conditions	Predisposing heart disease, previous IE, cardiac implantable electronic device (CIED), or injection drug use.
  	Fever	Temperature >38°C (100.4°F).
  	Vascular phenomena	Evidence of embolic or vascular complications.
  	Immunologic phenomena	Immunologic manifestations consistent with IE.
  	Microbiological evidence	Positive blood cultures or molecular tests that do not fulfill major criteria but are consistent with IE.
  	Additional imaging/clinical findings	Abnormal FDG-PET/CT after recent prosthetic implantation or new valvular regurgitation on auscultation when echocardiography is unavailable.