title: Establishment of a new methicillin resistant Staphylococcus aureus animal model of osteomyelitis.
abstract: OBJECTIVE
  The increase in methicillin-resistant Staphylococcus aureus (MRSA) infections is currently a major health care problem. Vancomycin is still often the first-line anti-microbiological agent for treating such infections; however, a recent decline in efficacy of vancomycin in MRSA infections has raised concerns and accelerated the search for new antibiotics. The aim of this study was to establish a MRSA peri-implant osteomyelitis animal model for future testing of new anti-microbiological agents under typical MRSA infection conditions.
  
  
  METHODS
  Eighteen randomised NZW-rabbits underwent a standardised surgical procedure with the insertion of a femoral bone implant. Animals were then divided into group 1 (MRSA inoculation, no antibiotics; M/N), group 2 (MRSA inoculation, Vancomyin; M/V), and group 3 (no MRSA inoculation, no antibiotics; N/N). The primary study outcome parameters were animal leucocyte count, animal weight, and animal body temperature at one, seven, and 42 days after surgery. Additionally, a histo-morphometrical score was established and adjusted to a modified histological Smeltzer score.
  
  
  RESULTS
  Macroscopic and histo-morphometrical findings showed a peri-implant osteomyelitis in group 1 with both increased acute and chronic infection parameters in M/N, as compared to M/V and N/N, indicating that vancomycin treatment prevented typical morphological changes of MRSA peri-implant osteomyelitis. Similarly, there was a reduction in animal weight and increase in leucocyte count and body temperature in group 1 (each p < 0.005). Vancomycin treatment again resulted in significantly reduced leucocyte count and body temperature, and increased animal body weight.
  
  
  CONCLUSIONS
  Here we have established a peri-implant MRSA osteomyelitis model that successfully combined clinical and laboratory outcome parameters of infection with histo-morphometrical results; this model appears to be valuable for future experimental use and therapeutic monitoring of new anti-microbiological MRSA drugs.
authors.affiliation: Department of Orthopedics, Trauma Surgery and Paraplegiology, Heidelberg University Hospital, Heidelberg, Germany.
authors.forename: Lars
authors.initials: L
authors.lastname: Helbig
authors.forename: Hans Georg
authors.initials: HG
authors.lastname: Simank
authors.forename: Helga
authors.initials: H
authors.lastname: Lorenz
authors.forename: Cornelia
authors.initials: C
authors.lastname: Putz
authors.forename: Christoph
authors.initials: C
authors.lastname: Wölfl
authors.forename: Arnold J
authors.initials: AJ
authors.lastname: Suda
authors.forename: Arash
authors.initials: A
authors.lastname: Moghaddam
authors.forename: Gerhard
authors.initials: G
authors.lastname: Schmidmaier
authors.forename: Thorsten
authors.initials: T
authors.lastname: Guehring
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000627:therapeutic use; D001831:Body Temperature; D018786:Bone Substitutes; D004195:Disease Models, Animal; D004352:Drug Resistance, Microbial; D007958:Leukocyte Count; D055624:Methicillin-Resistant Staphylococcus aureus; D008826:Microbial Sensitivity Tests; D010019:Osteomyelitis / Q000382:microbiology*; D011817:Rabbits; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D014640:Vancomycin / Q000008:administration & dosage / Q000627:therapeutic use
chemical_list: D000900:Anti-Bacterial Agents; D018786:Bone Substitutes; D014640:Vancomycin