Cephapirin therapy in infective endocarditis

Ten patients, eight of them heroin addicts, with infective endocarditis were treated with cephapirin. Causative organisms included Staphylococcus aureus in six patients and viridans streptococci, S bovis, and S pneumoniae in one patient each. In one of the patients with endocarditis, both S aureus and an organism of the beta-Streptococcus group were simultaneously isolated. All patients except two, both with monomicrobial S aureus endocarditis, were cured. All isolates were inhibited by less than or equal to 0.5 micrograms/ml of cephapirin. Peak serum bactericidal activity greater than or equal to 32 times the minimal inhibitory concentration (MIC) of the causative organism was achieved in all cases after giving 2 gm IV every four hours. After using large inoculums of staphylococci for in vitro tests, we found that twofold to eightfold increases in MIC occurred. Cephapirin was well tolerated intravenously and high levels in serum were achieved without toxicity or accumulation of the drug.