title: In vitro efficacy of antibiotic beads in treating abdominal vascular graft infections.
abstract: OBJECTIVE
  Abdominal aortic vascular graft infection often involves several different organisms. Antibiotic polymethyl methacrylate (PMMA) beads may be effective in controlling infection after débridement, but bacterial species identification and antibiotic susceptibility are often not available at the time of operation, generating a need for a broad-spectrum drug combination for empirical use. We sought to determine an effective antibiotic in PMMA beads for use in abdominal vascular graft infection.
  
  
  METHODS
  PMMA beads were impregnated with combinations of antibiotics, consisting of daptomycin, tobramycin, and meropenem. Antibiotics were selected on the basis of activity spectrum and heat stability. Beads were placed on separate agar plates with vancomycin-resistant Enterococcus faecalis, Klebsiella pneumoniae, Staphylococcus epidermidis, and methicillin-resistant Staphylococcus aureus. Antibiotic inhibition was recorded by use of a modified agar-based disk-diffusion method.
  
  
  RESULTS
  Daptomycin alone was not active against K. pneumoniae (average = 0 mm). Tobramycin alone was not active against vancomycin-resistant E. faecalis, K. pneumoniae, or methicillin-resistant S. aureus. Tobramycin and daptomycin in combination had moderate broad-spectrum activity with 8- to 14-mm mean inhibition halos. Meropenem showed strong activity against all tested organisms with >15-mm mean inhibition halos. The addition of daptomycin to meropenem provided improved coverage of gram-positive organisms. The presence of tobramycin reduced the efficacy of meropenem.
  
  
  CONCLUSIONS
  Antibiotic PMMA beads containing 10% meropenem with 2.5% daptomycin had excellent in vitro activity against typical bacterial species associated with abdominal vascular graft infections. The addition of antibiotic beads may be a useful adjunct in managing such cases. Further studies are required to determine efficacy in clinical practice.
authors.affiliation: Department of Cardiothoracic and Vascular Surgery, University of Texas Medical School at Houston, Houston, Tex; Memorial Hermann Heart and Vascular Institute-Texas Medical Center, Houston, Tex. Electronic address: kristofer.charltonouw@uth.tmc.edu.
authors.forename: Kristofer M
authors.initials: KM
authors.lastname: Charlton-Ouw
authors.affiliation: Department of Cardiothoracic and Vascular Surgery, University of Texas Medical School at Houston, Houston, Tex.
authors.forename: Fernando
authors.initials: F
authors.lastname: Kubrusly
authors.affiliation: Department of Cardiothoracic and Vascular Surgery, University of Texas Medical School at Houston, Houston, Tex.
authors.forename: Harleen K
authors.initials: HK
authors.lastname: Sandhu
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, Houston, Tex.
authors.forename: Michelle C
authors.initials: MC
authors.lastname: Swick
authors.affiliation: Department of Cardiothoracic and Vascular Surgery, University of Texas Medical School at Houston, Houston, Tex.
authors.forename: Samuel S
authors.initials: SS
authors.lastname: Leake
authors.affiliation: Memorial Hermann Heart and Vascular Institute-Texas Medical Center, Houston, Tex.
authors.forename: Brian E
authors.initials: BE
authors.lastname: Gulbis
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, Houston, Tex.
authors.forename: Theresa M
authors.initials: TM
authors.lastname: Koehler
authors.affiliation: Department of Cardiothoracic and Vascular Surgery, University of Texas Medical School at Houston, Houston, Tex; Memorial Hermann Heart and Vascular Institute-Texas Medical Center, Houston, Tex.
authors.forename: Hazim J
authors.initials: HJ
authors.lastname: Safi
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D001012:Aorta, Abdominal / Q000601:surgery*; D001807:Blood Vessel Prosthesis; D017576:Daptomycin / Q000008:administration & dosage; D066298:In Vitro Techniques; D000077731:Meropenem; D019904:Polymethyl Methacrylate; D013530:Surgical Wound Infection / Q000188:drug therapy*; D013845:Thienamycins / Q000008:administration & dosage; D014031:Tobramycin / Q000008:administration & dosage
chemical_list: D000900:Anti-Bacterial Agents; D013845:Thienamycins; D019904:Polymethyl Methacrylate; D000077731:Meropenem; D017576:Daptomycin; D014031:Tobramycin