Bacterial endocarditis is an infection of the inner lining of the heart, known as the endocardium. It occurs when bacteria enter the bloodstream and attach to damaged areas of the heart, often affecting heart valves. This condition can lead to serious complications, including heart failure and stroke. Risk factors for bacterial endocarditis include pre-existing heart conditions, artificial heart valves, and certain medical procedures. Symptoms may include fever, fatigue, and heart murmurs. Diagnosis typically involves blood tests and imaging studies, while treatment usually requires antibiotics and, in severe cases, surgery to repair or replace affected heart valves.