Endocarditis caused by Actinobacillus actinomycetemcomitans.

Actinobacillus actinomycetemcomitans, a small, gram-negative bacillus with fastidious growth requirements, is a rare cause of endocarditis. The clinical course of this disease is characterized by long duration of symptoms before diagnosis (average of three months), prolonged incubation before growth (average of six days), and a high embolic rate. The optimal antimicrobial regimen cannot be determined from available data, but the combination of ampicillin and an aminoglycoside may offer the best chance for cure. Two cases are presented, one successfully treated. Previously reported cases are reviewed.