Specific Therapy The American Heart Association recently published new guidelines for the management of IE, including specific treatment recommendations. These guidelines include primary and alternative regimens, as indicated in the treatment tables under strength of recommendation.

Surgery Surgical intervention has become an integral therapy in combination with pharmacologic management of IE. Valve replacement is the predominant intervention, and it is used in a minimum of 25% for all cases of IE.

Culture-Negative Endocarditis Negative blood cultures are present in about 5% to 10% of patients who meet strict criteria for the diagnosis of IE and have not recently received antibiotics. The prior administration of antimicrobials is thought to account for most cases of culture-negative endocarditis. Slow-growing and fastidious organisms, such as gramnegative bacilli in the Haemophilus-Actinobacillus- Cardiobacterium-Eikenella-Kingella (HACEK) group, Brucella, Coxiella, chlamydiae, strict anaerobes, and fungi, should be pursued in culture-negative patients.

Prophylactic Therapy Rationale and Recommendations Because infective endocarditis is associated with significant mortality and long-term morbidity, prevention in susceptible patients is of paramount importance. Estimates are, however, that <10% of all cases are theoretically preventable. Prophylactic antibiotics are thought to provide protection by decreasing the number of organisms reaching the damaged heart valve from a primary source. Thus, antibiotics theoretically prevent bacterial multiplication on the valve and interfere with bacterial adherence to the cardiac lesion.

Prophylactic Therapy Indications and Choice of Agent Presence of a prosthetic valve, valvular or congenital heart diseases while undergoing multiple tooth extractions places the patient at risk for developing endocarditis.