Bacterial endocarditis of an artificial heart valve (ribbed), gross specimen. Bacterial endocarditis is the inflammation of the inner lining of the heart (endocardium) and most commonly affects the heart valves. It can be a primary infection, for example, the bacteria could be introduced during valve replacement surgery, or a complication of another disease, such as colorectal cancer. Bacterial endocarditis very rarely occurs in a healthy heart. Symptoms include fever, a fast heart rate and weight loss. Treatment is with a long course of high-dose antibiotics.