Controversies in the prophylaxis of infective endocarditis: a cardiological view.

Antibiotic prophylaxis is logical but it is impossible to prove its efficacy. Most cases of infective endocarditis follow seemingly 'spontaneous' bacteraemias and cases of seemingly 'failed' prophylaxis may have done the same, the prophylaxis having been 'successful' for the occasion for which it was given. We cannot find out how many cases of infective endocarditis would have occurred but for successful prophylaxis.