title: Broad spectrum antimicrobial activity of melimine covalently bound to contact lenses.
abstract: OBJECTIVE
  To develop a stable antimicrobial contact lens, which is effective against the International Organization for Standardization (ISO) panel microorganisms, Acanthamoeba castellanii and drug resistant strains of Pseudomonas aeruginosa and Staphylococcus aureus.
  
  
  METHODS
  Melimine was covalently incorporated into etafilcon A lenses. The amount of peptide present on the lens surface was quantified using amino acid analysis. After coating, the heat stability (121°C), lens surface hydrophobicity (by captive bubble), and in vitro cytotoxicity to mouse L929 cells of the lenses were investigated. Antimicrobial activity against the micro-organisms was evaluated by viable plate count and fluorescence microscopy, measuring the proportion of cell death compared with control lenses with no melimine.
  
  
  RESULTS
  The most effective concentration was determined to be 152 ± 44 μg lens(-1) melimine on the lens surface. After coating, lenses were relatively hydrophilic and were nontoxic to mammalian cells. The activity remained high after autoclaving (e.g., 3.1, 3.9, 1.2, and 1.0 log inhibition against P. aeruginosa, S. aureus, A. castellanii, and Fusarium solani, respectively). Fluorescence microscopy confirmed significantly reduced (P < 0.001) adhesion of viable bacteria to melimine contact lenses. Viable count confirmed that lenses were active against all the bacteria and fungi from the ISO panel, Acanthamoeba and gave at least 2 log inhibition against all the multidrug resistant S. aureus and P. aeruginosa strains.
  
  
  CONCLUSIONS
  Melimine may offer excellent potential for development as a broad spectrum antimicrobial coating for contact lenses, showing activity against all the bacterial and fungal ISO panel microorganisms, Acanthamoeba, and antibiotic resistant strains of P. aeruginosa and S. aureus.
authors.affiliation: Brien Holden Vision Institute, Sydney NSW, Australia. debarun.dutta@unsw.edu.au
authors.forename: Debarun
authors.initials: D
authors.lastname: Dutta
authors.forename: Nerida
authors.initials: N
authors.lastname: Cole
authors.forename: Naresh
authors.initials: N
authors.lastname: Kumar
authors.forename: Mark D P
authors.initials: MD
authors.lastname: Willcox
mesh_terms: D048248:Acanthamoeba castellanii / Q000187:drug effects; D000562:Amebiasis / Q000517:prevention & control; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000494:pharmacology*; D045744:Cell Line, Tumor; D020099:Coated Materials, Biocompatible; D003261:Contact Lenses / Q000382:microbiology* / Q000469:parasitology; D024881:Drug Resistance, Bacterial; D015818:Eye Infections, Bacterial / Q000517:prevention & control*; D005354:Fibrosarcoma; D060585:Fusariosis / Q000517:prevention & control; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007634:Keratitis / Q000517:prevention & control; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry*; D051379:Mice; D011552:Pseudomonas Infections / Q000517:prevention & control; D013203:Staphylococcal Infections / Q000517:prevention & control
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D020099:Coated Materials, Biocompatible; D008689:Methacrylates; C114176:etafilcon; C541912:melimine