Streptococcus mutans endocarditis: report of three cases and review of the literature.

Our findings indicate that S. mutans endocarditis is capable of causing significant morbidity and mortality, as exemplified by the prolonged and complicated hospital course of our patients and the ultimate death of one of them. S. mutans endocarditis is probably underreported because most clinical laboratories do not speciate the viridans streptococci. Isolates of S. mutans should be tested for tolerance that would require the addition of an aminoglycoside to the penicillin regimen. Our experience agrees with the literature and indicates that S. mutans is primarily a pathogen in elderly patients with heart disease and may be associated with IHSS.