Right-sided Staphylococcus aureus endocarditis in intravenous drug abusers: two-week combination therapy

STUDY OBJECTIVE: To determine the efficacy of short-course combination regimens for selected cases of Staphylococcus aureus endocarditis in intravenous drug abusers. DESIGN: Open study of nafcillin and tobramycin or vancomycin and tobramycin administered for 2 weeks with no further therapy. SETTING: County hospital. PATIENTS: Consecutive sample of 53 intravenous drug abusers with relatively uncomplicated right-sided S. aureus endocarditis, defined by clinical and echocardiographic criteria, and without renal insufficiency, extrapulmonary metastatic infectious complications requiring prolonged therapy or surgery for cure, meningitis, methicillin-resistant organism, aortic or mitral valve involvement, or pregnancy. INTERVENTIONS: Nafcillin, 1.5 g intravenously every 4 hours, plus tobramycin, 1 mg/kg body weight intravenously every 8 hours, administered for 2 weeks. Vancomycin, 30 mg/kg per day intravenously, in two or three divided doses, was used instead of nafcillin for patients allergic to penicillin. MEASUREMENTS AND MAIN RESULTS: Forty-seven of 50 patients (94%; 95% CI, 87 to 99+) treated with the nafcillin and tobramycin combination were cured. Only 1 of 3 patients treated with vancomycin plus tobramycin (33%, 95% CI, 2 to 86) was cured. CONCLUSIONS: Selected patients with S. aureus endocarditis can be treated safely and effectively with a 2-week course of nafcillin plus tobramycin. Only one of three patients treated with vancomycin plus tobramycin was cured, but three patients are too few to define with confidence the efficacy of this regimen.