title: The effect of bacterial infection on the biomechanical properties of biological mesh in a rat model.
abstract: BACKGROUND
  The use of biologic mesh to repair abdominal wall defects in contaminated surgical fields is becoming the standard of practice. However, failure rates and infections of these materials persist clinically. The purpose of this study was to determine the mechanical properties of biologic mesh in response to a bacterial encounter.
  
  
  METHODS
  A rat model of Staphylococcus aureus colonization and infection of subcutaneously implanted biologic mesh was used. Samples of biologic meshes (acellular human dermis (ADM) and porcine small intestine submucosa (SIS)) were inoculated with various concentrations of methicillin-resistant Staphylococcus aureus [10(5), 10(9) colony-forming units] or saline (control) prior to wound closure (n = 6 per group). After 10 or 20 days, meshes were explanted, and cultured for bacteria. Histological changes and bacterial recovery together with biomechanical properties were assessed. Data were compared using a 1-way ANOVA or a Mann-Whitney test, with p<0.05.
  
  
  RESULTS
  The overall rate of staphylococcal mesh colonization was 81% and was comparable in the ADM and SIS groups. Initially (day 0) both biologic meshes had similar biomechanical properties. However after implantation, the SIS control material was significantly weaker than ADM at 20 days (p = 0.03), but their corresponding modulus of elasticity were similar at this time point (p>0.05). After inoculation with MRSA, a time, dose and material dependent decrease in the ultimate tensile strength and modulus of elasticity of SIS and ADM were noted compared to control values.
  
  
  CONCLUSIONS
  The biomechanical properties of biologic mesh significantly decline after colonization with MRSA. Surgeons selecting a repair material should be aware of its biomechanical fate relative to other biologic materials when placed in a contaminated environment.
authors.affiliation: Department of Surgery, Tulane University Health Sciences Center, New Orleans, Louisiana, United States of America. cbellows@tulane.edu
authors.forename: Charles F
authors.initials: CF
authors.lastname: Bellows
authors.forename: Benjamin M
authors.initials: BM
authors.lastname: Wheatley
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Moroz
authors.forename: Stephanie C
authors.initials: SC
authors.lastname: Rosales
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Morici
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D001696:Biomechanical Phenomena; D008297:Male; D023421:Models, Animal; D051381:Rats; D017207:Rats, Sprague-Dawley; D013203:Staphylococcal Infections / Q000382:microbiology / Q000503:physiopathology*; D013211:Staphylococcus aureus / Q000302:isolation & purification*; D013526:Surgical Mesh
chemical_list: D001672:Biocompatible Materials