title: Novel in vitro model for assessing susceptibility of synthetic hernia repair meshes to Staphylococcus aureus infection using green fluorescent protein-labeled bacteria and modern imaging techniques.
abstract: BACKGROUND
  Mesh infection complicating hernia repair is a major cause of patient morbidity and results in substantial healthcare expenditures. The various constructs of prosthetic mesh may alter the ability of bacteria to attach and form a biofilm. Few data exist evaluating biofilm formation. Using the Maestro in-Vivo Imaging System (CRi, Inc., Woburn, MA) to detect green fluorescent protein (GFP)-expressing Staphylococcus aureus, we studied the ability of synthetic mesh to withstand bacterial biofilm formation in an in vitro model.
  
  
  METHODS
  We included four meshes: Polypropylene (PP), polypropylene/expanded PTFE (PX), compressed PTFE (cPTFE), and polyester/polyethylene glycol and collagen hydrogel (PE). Five samples of each mesh were exposed to GFP-expressing S. aureus for 18 h at 37°C. Next, green fluorescence was measured using the Maestro Imaging System, with the results expressed in relative fluorescence units (RFU), subtracting the fluorescence of uninfected mesh (control). Each mesh subsequently underwent sonication and quantitative culture of the released bacteria, with the results expressed in colony-forming units (CFU). Analysis of variance was performed to compare the mean values for the different meshes.
  
  
  RESULTS
  There was a statistically significant difference in bacterial fluorescence for the four meshes: PE (49.9 ± 25.5 [standard deviation] RFU), PX (30.8 ± 9.4 RFU), cPTFE (10.1 ± 4.0 RFU), and PP (5.8 ± 7.5 RFU)(p = 0.001). Bacterial counts also were significantly different: PE (2.2 × 10(8) CFU), PX (8.6 × 10(7) CFU), cPTFE (3.7 × 10(7) CFU), and PP (9.1 × 10(7) CFU)(p < 0.001).
  
  
  CONCLUSIONS
  Using novel imaging technology, this study documented significantly different amounts of S. aureus biofilm formation and proliferation on different mesh constructs, with good agreement between imaging and culture results. A multifilament woven mesh (PE) had the highest degree of biofilm formation. These findings are being evaluated in a clinical infection model.
authors.affiliation: Case Western Reserve School of Medicine, Cleveland, OH, USA.
authors.forename: Ihab
authors.initials: I
authors.lastname: Halaweish
authors.forename: Karem
authors.initials: K
authors.lastname: Harth
authors.forename: Ann-Marie
authors.initials: AM
authors.lastname: Broome
authors.forename: Gabriela
authors.initials: G
authors.lastname: Voskerician
authors.forename: Michael R
authors.initials: MR
authors.lastname: Jacobs
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Rosen
mesh_terms: D058491:Bacterial Load / Q000379:methods; D018441:Biofilms / Q000254:growth & development*; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D059685:Herniorrhaphy; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D013010:Sonication; D013194:Staining and Labeling / Q000379:methods; D013211:Staphylococcus aureus / Q000235:genetics / Q000254:growth & development*; D013526:Surgical Mesh / Q000382:microbiology*
chemical_list: D049452:Green Fluorescent Proteins
references.citation: Zentralbl Bakteriol Mikrobiol Hyg A. 1984 Apr;256(4):479-89
references.pmid: 6741344
references.citation: J Vasc Surg. 1994 Mar;19(3):465-72
references.pmid: 8126859
references.citation: Surg Infect (Larchmt). 2007 Jun;8(3):337-41
references.pmid: 17635056
references.citation: J Clin Microbiol. 1985 Dec;22(6):996-1006
references.pmid: 3905855
references.citation: Surg Infect (Larchmt). 2007 Jun;8(3):405-14
references.pmid: 17635064
references.citation: Br J Surg. 2008 Aug;95(8):1051-9
references.pmid: 18618841
references.citation: Am Surg. 2003 Sep;69(9):784-7
references.pmid: 14509327
references.citation: Hernia. 2003 Sep;7(3):118-24
references.pmid: 12942345
references.citation: J Biomed Mater Res. 1998 Fall;43(3):338-48
references.pmid: 9730073
references.citation: J Orthop Res. 1984;2(3):269-71
references.pmid: 6491817
references.citation: Hernia. 2001 Sep;5(3):148-52
references.pmid: 11759801
references.citation: Appl Environ Microbiol. 1979 Jan;37(1):67-72
references.pmid: 16345338
references.citation: J Biomed Mater Res A. 2007 Mar 1;80(3):742-51
references.pmid: 17177270
references.citation: Ann Surg. 2001 Jan;233(1):26-33
references.pmid: 11141221
references.citation: South Med J. 2003 Mar;96(3):254-8
references.pmid: 12659356
references.citation: Ostomy Wound Manage. 2002 Oct;48(10):40-2, 44-5
references.pmid: 12378002
references.citation: Biomaterials. 2007 May;28(14):2314-27
references.pmid: 17306365
references.citation: Infect Immun. 2002 Nov;70(11):6339-45
references.pmid: 12379713
references.citation: N Engl J Med. 2000 Aug 10;343(6):392-8
references.pmid: 10933738
references.citation: J Gen Microbiol. 1983 Sep;129(9):2959-68
references.pmid: 6631420
references.citation: J Biomed Mater Res. 1999 Mar 5;44(3):261-5
references.pmid: 10397928
references.citation: Clin Microbiol Infect. 2005 Jan;11(1):3-8
references.pmid: 15649297
references.citation: Surg Endosc. 2005 Mar;19(3):430-5
references.pmid: 15580439
references.citation: J Surg Res. 2009 Nov;157(1):e79-86
references.pmid: 19592038
references.citation: Hernia. 2006 Apr;10(2):120-4
references.pmid: 16453077
references.citation: J Biomed Mater Res. 2002;63(6):765-71
references.pmid: 12418022