Infective endocarditis is a microbial infection of the endocardial surface of the heart. The characteristic lesion, a vegetation, is composed of a collection of platelets, fibrin, microorganisms, and inflammatory cells. It most commonly involves heart valves but may also occur at the site of a septal defect, on the chordae tendineae, or on the mural endocardium. Staphylococci and streptococci account for 80% of cases of infective endocarditis, with staphylococci currently the most common pathogens. Cerebral complications are the most frequent and most severe extracardiac complications.