An infection of the lining of the heart chambers and heart valves by bacteria, fungi, viruses, or other microorganisms. Bacterialendocarditis refers specifically to infection by a bacterial agent.

nfectious endocarditis may involve the heart muscle, heart valves, or lining of the heart. Most people who develop infectiousendocarditis have underlying heart disease . Sources of the infection may be transient bacteremia, which is common duringdental, upper respiratory, urologic, and lower gastrointestinal diagnostic and surgical procedures. The infection causes growthson the heart valves, the lining of the heart, or the lining of the blood vessels. These growths may be dislodged and send clots tothe brain, lungs, kidneys, or spleen. The incidence is 5 out of 100,000 people.Many bacteria can cause endocarditis but a common mouth organism, Streptococcus viridans, is responsible for approximatelyhalf of all bacterial endocarditis. Other common organisms include staphylococcus and group D streptococcus. Less commonorganisms include Pseudomonas, Serratia, Candida, and many others.Endocarditis may develop symptoms slowly (subacute) or suddenly (acute) . Fever is a hallmark of both. In the slower form,fever may be present on a daily basis for months before other symptoms appear. Other symptoms are nonspecific such as fatigue,malaise (general discomfort), headache, and night sweats. As the illness progresses, small dark lines, called splinterhemorrhages, may appear under the fingernails. The health care provider may hear changing murmurs and detect an enlargedspleen and mild anemia. Murmurs are caused when clumps of bacteria, fibrin and cellular debris, called vegetations, collect onthe heart valves. The mitral valve is the most common valve affected, followed by the aortic valve.Preexisting conditions that increase the likelihood of developing endocarditis include:- congenital heart disease: ASD (atrial septal defect) , PDA (patent ductus arteriosus) , and others.- prior rheumatic heart disease- cardiac valve anomalies (such as mitral insufficiency)- prosthetic heart valvesSince Streptococcus viridans is a common mouth organism and the most common cause of bacterial endocarditis, dentalprocedures can put children with congenital heart conditions at risk for endocarditis. It is common practice for children withsome forms of congenital heart disease to start on antibiotics prior to any dental procedures.

Preventive (prophylactic) antibiotics are often given to people with predisposing congenital or valvular abnormalities beforedental procedures or surgeries involving the respiratory, urinary, or intestinal tract. Continued medical follow-up is advised forpeople with a previous history of infective endocarditis.