Infective endocarditis (IE) is a microbial infection of the endocardium. In subacute IE, the previously-damaged surface of cardiac valve becomes the starting point for the deposition of platelets and the formation of a platelet-fibrin clot. IE develops after bacteria enters the bloodstream and colonize the clot. Platelets and fibrin mount up over the bacteria, increasing the size of the vegetation. As additional layers of fibrin are added, leukocytes are incapable to break through the vegetation. Treatment with antibiotics can also be problematic because the bacteria within the vegetation often become less metabolically active, and many antibiotics require active bacterial growth to be effective. The overall incidence of infective endocarditis is 1.7 to 4.0 per 100,000 population and in adults older than 50 years, it exceeds 15 per 100,000 population. Almost 50-60% of cases of acute IE do not necessitate an underlying heart condition to be present. The microorganisms most accountable for the development of acute IE (e.g. S. aureus) are exceedingly virulent and able to colonize normal heart valves. The incidence of acute IE has been progressively rising and now surpasses the number of subacute IE cases. Presenting symptoms and clinical signs include fever, malaise, weight loss, splenomegaly, cardiac murmur, petechiae, Roth's spots, Janeway lesions and Osler nodes. This book provides leading-edge research on this field from around the world.