title: β-Lactams enhance vancomycin activity against methicillin-resistant Staphylococcus aureus bacteremia compared to vancomycin alone.
abstract: Vancomycin (VAN) is often used to treat methicillin-resistant Staphylococcus aureus (MRSA) bacteremia despite a high incidence of microbiological failure. Recent in vitro analyses of β-lactams in combination with VAN demonstrated synergistic activity against MRSA. The goal of this study was to examine the impact of combination therapy with VAN and a β-lactam (Combo) on the microbiological eradication of MRSA bacteremia compared to VAN alone. This was a retrospective cohort study of patients with MRSA bacteremia who received Combo therapy or VAN alone. Microbiological eradication of MRSA, defined as a negative blood culture obtained after initiation of therapy, was used to evaluate the efficacy of each regimen. A total of 80 patients were included: 50 patients in the Combo group and 30 patients in the VAN-alone group. Microbiological eradication was achieved in 48 patients (96%) in the Combo group compared to 24 patients (80%) in the VAN-alone group (P = 0.021). In a multivariable model, the Combo treatment had a higher likelihood of achieving microbiological eradication (adjusted odds ratio, 11.24; 95% confidence interval, 1.7 to 144.3; P = 0.01). In patients with infective endocarditis (n = 22), 11/11 (100%) who received Combo therapy achieved microbiological eradication compared to 9/11 (81.8%) treated with VAN alone, but the difference was not statistically significant (P = 0.20). Patients with MRSA bacteremia who received Combo therapy were more likely to experience microbiological eradication of MRSA than patients who received VAN alone.
authors.affiliation: Department of Pharmacy Practice and Administrative Sciences, University of New Mexico College of Pharmacy, Albuquerque, New Mexico, USA.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Dilworth
authors.forename: Omar
authors.initials: O
authors.lastname: Ibrahim
authors.forename: Pamela
authors.initials: P
authors.lastname: Hall
authors.forename: Jora
authors.initials: J
authors.lastname: Sliwinski
authors.forename: Carla
authors.initials: C
authors.lastname: Walraven
authors.forename: Renée-Claude
authors.initials: RC
authors.lastname: Mercier
mesh_terms: D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000627:therapeutic use*; D016470:Bacteremia / Q000188:drug therapy*; D005260:Female; D006801:Humans; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000472:pathogenicity*; D008875:Middle Aged; D012189:Retrospective Studies; D016896:Treatment Outcome; D014640:Vancomycin / Q000008:administration & dosage / Q000627:therapeutic use*; D047090:beta-Lactams / Q000008:administration & dosage / Q000627:therapeutic use*
chemical_list: D000900:Anti-Bacterial Agents; D047090:beta-Lactams; D014640:Vancomycin