Culture-negative infective endocarditis

Culture-negative endocarditis is not uncommon; the most frequent causes of the culture negative state are prior antibiotic therapy and problems with or inadequacies in bacteriologic technique. In addition to blood culture, studies that can aid in substantiating a presumptive diagnosis of infective endocarditis include echocardiography. Immunologic tests, and cardiac catheterization. Empiric antibiotic therapy often is necessary and should not be delayed to await positive blood cultures and results of antimicrobial sensitivity studies.