The presentation of this case of endocarditis due to A actinomycetemcomitans is typical for this organism. Septicemia with this organism is essentially always associated with endothelial infection, and an abnormal echocardiogram confirmed the diagnosis of endocarditis; however, all previously published cases of native valvular infections with this organism involved the left-sided cardiac valves. In these patients, major emboli were common, occurring in approximately 50 percent of the cases, with cerebral emboli in about
25 percent. Congestive heart failure developed in approximately 50 percent, and one-third of all cases were fatal. In the present case, gingival infection was undoubtedly the principal site of entry and gingival surgery the probable cause. Despite the fact that this is the usual portal of entry in infections with this organism, localization of this organism to a right-sided native cardiac valve, as in this case, is extremely unusual. This patient had no prior history of cardiovascular symptoms, cardiac murmur, intravenous drug abuse, or familial heart disease. The findings from the physical examination, the chest x-ray film, and the electrocardiogram also confirmed the impression of no prior significant heart disease. Nevertheless, a preexisting isolated anatomic abnormality of the tricuspid valve of no hemodynamic consequence cannot be entirely excluded.
The M-mode echocardiogram is generally satisfactory for visualization of aortic and mitral valvular vegetations, particularly if the vegetations are at least 3 cm in diameter; however, the M-mode technique is suboptimal for examination of the tricuspid and pulmonic valves. Because of the slow growth of the pathogen and normal initial M-mode echocardiogram, the correct diagnosis and treatment were delayed. In addition to the delay, further diagnostic tests were performed in the interim, resulting in unnecessary risk and expense to the patient. Isolation of the organism and twodimensional echocardiographic demonstration of a large tricuspid valvular vegetation ultimately confirmed the diagnosis. It is suggested, therefore, that a complete twodimensional echocardiographic examination of the left and right side of the heart is indicated for all patients with suspected endocarditis, even in circumstances where only left-sided cardiac involvement is anticipated.
Ampicillin alone (12 g/day intravenously) has been suggested as adequate and optimal therapy for endocarditis due to A actinomycetemcomitans occurring on a native valve, in combination with an aminoglycoside for prosthetic valvular endocarditis. This approach was successful in the treatment of the present case. The renal lesion in this patient was presumed to be a complication of endocarditis; the patients renal function has remained stable during the six-month follow-up.