The changing character of infective endocarditis.

The presentation and course of infective endocarditis is changing because there is an increasing number of resistant organisms which are causative agents. At present, resistant organisms are isolated in more than one-half of the cases; Streptococcus viridans is found in only 40 percent. The increased use of antimicrobial agents, the frequent use of intravenous heroin and the increased amount of cardiac surgery have been important in increasing the number of resistant organisms and providing convenient access routes to the circulation.