Daptomycin compared to vancomycin for the treatment of osteomyelitis: a single-center, retrospective cohort study.

BACKGROUND: Osteomyelitis (OM) is a serious infection with high rates of recurrence. Vancomycin has been used for decades in the treatment of OM, but, despite adequate dosing, 30% to 50% of patients experience infection recurrence within 12 months. Daptomycin, a novel lipopetide antibiotic, is also active against resistant gram-positive organisms, but there is little published about its efficacy and tolerability in the treatment of OM.

OBJECTIVE: Our aim was to compare the recurrence rates of OM in patients treated with daptomycin or vancomycin.

METHODS: A retrospective cohort study of all patients at a VA Medical Center between January 1, 2003, and July 31, 2009, who received daptomycin for the treatment of OM was undertaken. Patients with a diagnosis of OM who received at least 2 weeks of daptomycin and had at least 1 follow-up visit within 6 months after completion of therapy were included. Each patient was matched with 2 controls treated with at least 2 weeks of vancomycin for OM. Matching criteria included previous OM, diabetes, peripheral vascular disease, hardware involvement, and surgical therapy. Patients were excluded from the evaluation if they received <14 days of therapy, had no follow-up in the 6 months after therapy was discontinued, had an absolute neutrophil count <500 cells/mm(3), or were receiving vancomycin and daptomycin concurrently. The primary outcome was recurrence of infection within 6 months after the discontinuation of therapy. Secondary outcomes included mean change in creatine phosphokinase (CPK), incident thrombocytopenia, and mean doses of antibiotics. The χ(2) test was used to compare rates of recurrence between groups.

RESULTS: Seventeen patients received at least 2 weeks of daptomycin for the treatment of OM and were matched to 34 vancomycin controls. Twenty-nine percent of patients receiving daptomycin had a recurrence of infection compared with 61.7% in the vancomycin group (P = 0.029). The mean change in CPK for the daptomycin group was +28.8 U/L. No thrombocytopenia developed in any patients receiving daptomycin compared with 2 (5.9%) patients in the vancomycin group.

CONCLUSIONS: In a limited number of cases, significantly fewer patients treated with daptomycin for OM had a recurrence of their infection. Daptomycin may be a tolerable and effective alternative to vancomycin for the treatment of OM.