Henry Ford Hospital Medical Journal


Of 135 patients with streptococcal (non-group D) endocarditis seen at the Henry Ford Hospital (1957-1973), 133 had isolates which were penicillin- sensitive (inhibited by ≤ 0.2 μg/ml of penicillin C). The remaining two causative organisms were inhibited by 0.8 μg/ml of penicillin G and both of the infected patients received antibiotics just prior to the onset of endocarditis. The first patient received oral penicillin C for rheumatic fever prophylaxis and the second high dose parenteral carbenicillin. Using high dose parenteral therapy with ampicillin and streptomycin, the first patient was cured while the other patient relapsed. The second patient responded to retreatment with clindamycin. As reported in prior studies following oral penicillin administration, these current studies demonstrated penicillinresistant viridans streptococci in the oropharynx of patients receiving parenteral carbenicillin (avg. MIC 0.56 μg/ml). Therefore, carbenicillin-induced changes in the oral flora are important in selecting antibiotics for prophylaxis or treatment of endocarditis in a patient with pre-existing valvular disease.