[New etiologies responsible for infective endocarditis with negative blood cultures].

The prevalence of infective endocarditis with negative blood cultures varies in the different series from 5 to 25%. There are certain explanations of negative blood culture endocarditis: previous incorrect antibiotic therapy before obtaining blood samples (antibiotic treatment inhibits the growth of germs, and therefore bacteremia, without sterilizing the vegetations); infective endocarditis due to fastidious microorganism, that is of difficult cultivation and identification; infective endocarditis due to cell-dependent organism (e.g.