Infective endocarditis (IE) is a microbial infection of the endothelial layer of the heart, the valves or both. The mitral valve is most commonly affected, except in patients with intravenous drug use (IVDU), where the tricuspid valve is more commonly affected. Risk factors include age, chronic hemodialysis, poor dentition, valvulopathy, immunocompromised status, diabetes, IVDU, prosthetic valve and implanted cardiac devices. More than 50% of cases of IE occur in patients older than 60 years.

The majority of cases are due to Gram-positive cocci such as Staphylococcus and Streptococcus species. In patients with negative blood cultures and no recent antibiotic use, the organisms are often the HACEK group (Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella). Approximately 50% of patients require surgical management.