Infective endocarditis is an infection that occurs most often in people with preexisting heart valve problems. It can be diagnosed using the Duke Criteria, which looks for two major factors or one major and three minor factors related to things like blood culture results, echocardiogram findings, fever, and risk factors. Treatment involves empiric antibiotic therapy for several weeks tailored to the individual's history and any devices, and sometimes surgery is needed if the infection causes severe valve damage or other complications.