Endocarditis due to Actinomyces viscosus

We report a case of endocarditis caused by Actinomyces viscosus in a previously healthy young adult with no known identifiable portal of entry. Infective endocarditis caused by A viscosus is uncommon; two cases of endocarditis caused by this species have been previously reported. Primary actinomycotic endocarditis has been previously reviewed in 1993; we provide a review of additional cases since that report. In comparing our case with the other reported cases, we found that actinomycotic endocarditis (1) occurs in a wide spectrum of age, (2) affects primarily males, (3) has a high propensity for systemic embolization, and (4) has involved only native heart valves. The disease is manifested by the typical signs and symptoms of infective endocarditis and is curable with long-term penicillin therapy. The use of echocardiography in the diagnosis of endocarditis, techniques for improving the microbiologic diagnosis of endocarditis, and current indications for surgical intervention are discussed.