The AHA/ACC 2007 guidelines (reaffirmed in subsequent updates) dramatically narrowed IE prophylaxis indications based on evidence that (1) everyday bacteremia from chewing and tooth brushing causes more cumulative exposure than single dental procedures, (2) IE prophylaxis prevents only a small number of cases, and (3) antibiotic risks (allergic reactions, resistance) may outweigh benefits in low-risk patients. Prophylaxis is now recommended ONLY for patients at HIGHEST RISK of adverse outcomes from IE (not all patients at increased IE risk): prosthetic cardiac valves (mechanical or bioprosthetic), previous IE (recurrence rate 4-10%), certain congenital heart disease (unrepaired cyanotic CHD, completely repaired CHD with prosthetic material during the first 6 months after repair, repaired CHD with residual defects adjacent to prosthetic material), and cardiac transplant recipients with valvulopathy. Prophylaxis is indicated only for DENTAL procedures involving manipulation of gingival tissue, the periapical region of teeth, or perforation of oral mucosa (NOT routine anesthesia through non-infected tissue, placement of orthodontic brackets, or shedding of deciduous teeth). Gastrointestinal and genitourinary procedures NO LONGER require prophylaxis. Standard regimen: amoxicillin 2g PO 30-60 minutes before the procedure (adults);...