title: Biofilm Formation by Staphylococcus epidermidis on Foldable and Rigid Intraocular Lenses.
abstract: BACKGROUND
  Biofilm formation of Staphylococcus epidermidis is a major etiological factor of inducing device-related infections.
  
  
  OBJECTIVE
  The ability of biofilm formation by the S. epidermidis was assessed in vitro on two brands of foldable (hydrophilic) and two brands of rigid (hydrophobic) intraocular lens materials in order to investigate the role of lens material in postoperative endophthalmitis.
  
  
  METHODS
  To ensure reproducibility of biofilm formation on intraocular lenses, two strains of S. epidermidis and three quantification methods were performed. The S. epidermidis strains, DSMZ3270 (biofilm-producer) and ATCC12228 (non-biofilm-producer) were applied. Organisms were cultivated on disks of different brands of foldable hydrophilic Intra Ocular Lens (IOL) made of acrylic (Didar, Iran; (A) and Omni, India; (B)), and rigid hydrophobic IOL made of polymethyl methacrylate (PMMA; Didar, Iran; (C) and Hexavision, France; (D)). Biofilms were stained with crystal violet (CV) dye, which is an index of biofilm formation. The bacterial population was counted after biofilm homogenization. Scanning electron microscopy (SEM) was performed to examine the extent of biofilm formation.
  
  
  RESULTS
  Adherence of DSMZ3270 strain on both types of foldable and rigid IOLs, was significantly more than ATCC12228 (P < 0.001-0.05 and, P < 0.01-0.05, respectively). The bacterial populations between the lenses were significantly different (P < 0.05). Subsequent studies demonstrated significant differences between brands of foldable and PMMA IOLs. According to statistical analyses the incubation time influenced the biofilm formation on both types of IOLs which meant that by increasing incubation time, the biofilm formation increased. According to the SEM pictures, biofilm seems to be lysed at 72 hours.
  
  
  CONCLUSIONS
  These data demonstrated that the attachment of bacteria to hydrophilic acrylic IOLs was more than hydrophobic PMMA ones independent of the brand. According to these results the bacterial strain might have more hydrophilic properties. Augmenting the biomass of biofilm by passing of time demonstrated the key role of time in biofilm formation on the IOL surfaces. The differences between IOL brands in the biofilm formation indicated the influence of design parameters for IOLs.
authors.affiliation: Biotechnology Research Centre, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, IR Iran.
authors.forename: Bibi Sedigheh
authors.initials: BS
authors.lastname: Fazly Bazzaz
authors.affiliation: Biotechnology Research Centre, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, IR Iran.
authors.forename: Monireh
authors.initials: M
authors.lastname: Jalalzadeh
authors.affiliation: Biotechnology Research Centre, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, IR Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Sanati
authors.affiliation: School of Medicine, Mashhad University of Medical Sciences, Mashhad, IR Iran.
authors.forename: Syamak
authors.initials: S
authors.lastname: Zarei-Ghanavati
authors.affiliation: Department of Food and Drug Control, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, IR Iran.
authors.forename: Bahman
authors.initials: B
authors.lastname: Khameneh
keywords: Biofilms; Endophthalmitis; Lenses, Intraocular; Staphylococcus epidermidis