Background and methods: Nine patients with cardiovascular implantable electronic device (CIED) endocarditis were treated with daptomycin after the failure of previous treatment. The blood and CIED lead cultures of 1 patient were negative. In the other 8 patients, we observed 6 monomicrobic infections and 2 polymicrobic infections. Overall, 10 strains were isolated in these patients: 4 methicillin-sensitive Staphylococcus aureus, 2 methicillin-sensitive Staphylococcus epidermidis, 1 methicillin-resistant Staphylococcus aureus, 1 methicillin-resistant Staphylococcus epidermidis, 1 methicillin-sensitive Staphylococcus hominis, and 1 Propionibacterium acnes. The CIED was removed transvenously in 7 patients. Two patients were too sick for the removal of their CIED, and were cured with 6 mg/kg of daptomycin for 60 and 110 days, respectively, without adverse events.
Results: One patient died 4 days after the removal of his CIED because of a complicated abdominal aortic aneurysm. The other 8 patients were cured, with a mean follow-up of 17 ± 8 months. The removed leads were negative, after daptomycin therapy, in 4 cases out of 7. The mean ratio between peak daptomycin concentration and minimal inhibitory concentration (MIC) of the causative strains was 38.3 ± 18.5. For patients whose data were available, the ratio between peak daptomycin concentration and minimal bactericidal concentration (MBC) was 13.2 ± 3.2.
Conclusion: Daptomycin monotherapy may be a useful therapeutic tool in difficult-to-treat CIED endocarditis, resulting in a high rate of cures and sterilized leads removed. The ratio between peak daptomycin concentration and MIC or MBC may be useful as predictive tool for treatment success.
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