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Phat Tran, Abdul Hamood, Courtney Jarvis, Josh Thomas, Blake Lackey, Thomas Mosley, Ted Reid; Organo-Selenium Coated Contact Lenses: Effect Upon Bacterial Biofilm Attachment. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6086.
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Bacterial biofilm on contact lenses has been cited as a possible cause of corneal infection and acute red eye. A contact lens coating that blocks biofilm formation might reduce the frequency of these clinically significant problems. Selenium compounds can catalyze the formation of superoxide radicals in the tear film, which are cytotoxic to bacteria. Thus, this study investigated the effectiveness of a covalent organo-selenium coating on polyHEMA (Acuvue2) contact lenses.
The contact lenses were coated with organo-selenium compounds via wet chemistry covalent bond formation. The inhibition of biofilm formation with the organo-selenium coating was investigated by incubating organo-selenium coated and uncoated contact lenses in a nutrient broth containing, either Pseudomonas aeruginosa, Serratia marcescens or Staphylococcus aureus for 24 hours at 37oC. Biofilms were quantified by determining the CFU per lens. To determine the CFU/lens, each lens was gently rinsed with sterile distilled H2O, and placed into a microcentrifuge tube containing 1 ml phosphate buffered saline (PBS), and then vigorously vortexed three times for 1 min vortex to detach the cells. Suspended cells were serially diluted 10-fold in PBS and 10-μl aliquots of each dilution were spotted on LB agar plates. The plates were incubated at 37oC for 24 hours and the CFU were counted. For confocal laser scanning microscopy (CLSM), we used the S. aureus strain AH1333 and the P. aeruginosa strain PAO1-GFP strains. Both strains carry the gene that encodes the green fluorescent protein. For scanning election microscopy (SEM), the lenses were fixed in 3% glutaraldehyde and then imaged.
Colony forming unit assays showed total inhibition, representing over 6 logs of bacterial killing on contact lenses coated with organo-selenium compounds. Scanning election microscopy and confocal laser scanning microscopy confirmed these results.
The organo-selenium coating successfully blocked the formation of a bacterial biofilm on the polyHEMA (Acuvue2) contact lenses for Pseudomonas aeruginosa, Serratia marcescens and Staphylococcus aureus in vitro.
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