title: Evidence of MRSE on a gentamicin and vancomycin impregnated polymethyl-methacrylate (PMMA) bone cement spacer after two-stage exchange arthroplasty due to periprosthetic joint infection of the knee.
abstract: BACKGROUND
  Periprosthetic joint infections (PJI) are often treated by two stage exchange with the use of an antibiotic impregnated spacer. Most of the two-stage exchange algorithms recommend the implantation of an antibiotic-impregnated spacer during the first stage for a period of 2-24 weeks before reimplantation of the new prosthesis. For the spacer to have a therapeutic effect, the local antibiotic concentration must be greater than the minimal inhibition concentration (MIC) against the pathogens causing the PJI. It must remain so for the entire spacer period, otherwise recurrence of infection or resistances might occur. The question as to whether a sufficient concentration of antibiotics in vivo is reached for the entire spacer period has not been answered satisfactorily.
  
  
  METHODS
  We here present a case of a histologically confirmed chronic PJI 20 month after primary arthroplasty. The primary knee arthroplasty was performed due to osteoarthritis of the joint. Initial assessment did not detect a causative pathogen, and two stage exchange with a vancomycin-gentamycin impregnated spacer was performed. At the time of reimplantation, sonication of the explanted spacer revealed a multi-resistant strain of staphylococcus epidermidis on the device and in the joint. Adaption of the therapy and prolonged treatment successfully eradicated the infection.
  
  
  CONCLUSIONS
  According to the authors' knowledge, the case presented here confirms for the first time the surface contamination (proven through sonication) of a vancomycin-/gentamicin- impregnated Vancogenx®-spacer with a MRSE after ten weeks of implantation.This case study demonstrates the difficulties still associated with the diagnostics of PJI and the published different two stage treatment regimes with the use of antibiotic impregnated spacers.
authors.forename: Jan
authors.initials: J
authors.lastname: Schmolders
authors.forename: Gunnar T R
authors.initials: GT
authors.lastname: Hischebeth
authors.forename: Max J
authors.initials: MJ
authors.lastname: Friedrich
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Randau
authors.forename: Matthias D
authors.initials: MD
authors.lastname: Wimmer
authors.forename: Hendrik
authors.initials: H
authors.lastname: Kohlhof
authors.forename: Ernst
authors.initials: E
authors.lastname: Molitor
authors.affiliation: Department for Orthopaedic and Trauma Surgery, Rheinische Friedrich-Wilhelms-University Bonn, Sigmund-Freud-Strasse 25, 53105 Bonn, Germany. sascha.gravius@ukb.uni-bonn.de.
authors.forename: Sascha
authors.initials: S
authors.lastname: Gravius
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects; D001843:Bone Cements; D024901:Drug Resistance, Multiple, Bacterial; D005839:Gentamicins / Q000008:administration & dosage*; D006801:Humans; D007719:Knee Joint / Q000601:surgery; D008297:Male; D008875:Middle Aged; D019904:Polymethyl Methacrylate; D016459:Prosthesis-Related Infections / Q000188:drug therapy / Q000382:microbiology* / Q000517:prevention & control; D012086:Reoperation; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000209:etiology* / Q000382:microbiology; D013212:Staphylococcus epidermidis / Q000187:drug effects / Q000302:isolation & purification*; D016896:Treatment Outcome; D014640:Vancomycin / Q000008:administration & dosage*
chemical_list: D000900:Anti-Bacterial Agents; D001843:Bone Cements; D005839:Gentamicins; D014640:Vancomycin; D019904:Polymethyl Methacrylate