in diameter conduction defects rapid clinical response and clearance of bloodstream infection additionally, oxacillin-susceptible staphylococcus aureus native valve endocarditis of the right side can also be treated with a short 2-week course of a beta-lactam antibiotic such as nafcillin with or without aminoglycosides. histopathology of a vegetation of bacterial endocarditis, taken from a valve repair, h&e stain. in a consistent clinical setting, neutrophils and fibrin is enough to diagnose a bacterial vegetation, even without visible bacterial colonies. the main indication for surgical treatment is regurgitation or stenosis. in active infective endocarditis, the surgery should remove enough leaflet tissue to ensure eradication of the infectious process. subsequent valve repair can be performed in limited disease. replacement of the valve with a mechanical or bioprosthetic artificial heart valve is necessary in certain situations: patients with significant valve stenosis or regurgitation causing heart failure evidence of hemodynamic compromise in the form of elevated end-diastolic left ventricular or left atrial pressure or moderate to severe pulmonary hypertension presence of intracardiac complications like paravalvular abscess, conduction defects or destructive penetrating lesions recurrent septic emboli despite appropriate antibiotic treatment large vegetations (> 10 mm) persistently positive blood cultures despite appropriate antibiotic treatment prosthetic valve dehiscence relapsing infection in the presence of a prosthetic valve abscess formation early closure of mitral valve infection caused by fungi or resistant gram-negative bacteria. the guidelines were recently updated by both the american college of cardiology and the european society of cardiology. there was a recent meta-analysis published that showed surgical intervention at seven days or less is associated with lower mortality. prognosis infective endocarditis is associated with 18% in-hospital mortality. as many as 50% of people with infective endocarditis may experience embolic complications. epidemiology in developed countries, the annual incidence of infective endocarditis is 3 to 9 cases per 100,000 persons. infective endocarditis occurs more often in men than in women. there is an increased incidence of infective endocarditis in persons 65 years of age and older, which is probably because people in this age group have a larger number of risk factors for infective endocarditis. in recent years, over one-third of infective endocarditis cases in the united states was healthcare-associated. another trend observed in developed countries is that chronic rheumatic heart disease accounts for less than 10% of cases. although a history of valve disease has a significant association with infective endocarditis, 50% of all cases develop in people with no known history of valvular disease. history few diseases present greater difficulties in the way of diagnosis than malignant endocarditis, difficulties which in many cases are practically insurmountable. it is no disparagement to the many skilled physicians who have put their cases upon record to say that, in fully one-half the diagnosis was made post mortem.— william osler, 1885 lazare riviére first described infective endocarditis affecting the aortic valve in 1616. in 1806, jean-nicolas corvisart coined the term vegetation to describe collections of debris found on a mitral valve affected by infective endocarditis. the british physician joseph hodgson was the first to describe the embolic complications of infective endocarditis in 1815. it was not until 1878 that theodor klebs first suggested that infective endocarditis had a microbial infectious origin. in 1909, william osler noted that heart valves that experienced degeneration and were sclerotic or poorly functioning had a higher risk of being affected. later, in 1924, emanuel libman and benjamin sacks described cases of vegetative endocarditis that lacked a clear microbial origin and were often associated with the autoimmune condition systemic lupus erythematosus. in 1944, physicians reported on the first successful use of penicillin to treat a case of infective endocarditis.