Infective (or Bacterial) Endocarditis is a serious infection of the endocardium, the smooth interior lining of the heart, and of the heart's valves.

The infection is usually caused by bacteria, but in rare cases, fungi or other organisms may be responsible. The organisms usually enter the body through intravenous drug use, invasive medical or dental procedures (such as cardiac catheterizations or minor surgeries), cuts or bruises or the route is unclear.

Two types of this non-contagious disease are recognized:

= Acute Infective Endocarditis usually comes on suddenly and may become life-threatening within a matter of days. This type of Infective Endocarditis is usually caused by staphylococci, streptococci, pneumococci, or gonococci bacteria.

= Subacute (or Bacterial) Infective Endocarditis (sometimes called SBE) develops gradually over a period of weeks or months. It is usually caused by haemophilus bacteria or by different forms of streptococci than those that cause the acute form of the disease.

Infective Endocarditis is most common among men in their 50's and especially prevalent among African-Americans. Nearly two thirds of cases occur in conjunction with pre-existing heart conditions, surgeries, or defects.

Patients with congenital heart defects are especially prone to endocarditis. Blood moves at high velocity across defects such as VSD's, stenotic or leaky valves, and PDA's. This high velocity flow facilitates the sticking of the blood's clotting elements to these defects. If bacteria are in the blood stream, they become enveloped in the clot adhering to the defect and endocarditis may develop there.