Streptococcus mutans Endocarditis

Nine patients with Streptococcus mutans endocarditis were seen between 1966 and 1973. They had the typical clinical picture of subacute bacterial endocarditis, with fever, heart murmur, and multiple positive blood cultures. Five had a history of oral surgery; seven had prior known heart disease. All our isolates of S. mutans were inhibited by penicillin G at 0.1 μg/ml or less; minimal bactericidal concentrations ranged from 1.25 to 50 μg/ml. All patients were treated with penicillin G and streptomycin for 14 to 36 days and cured. It is clinically important to differentiate this organism from group D streptococci to avoid the prolonged therapy necessary to treat the latter type of endocarditis.