A Novel Antibiofilm Technology for Contact Lens Solutions

Abstract

Nonsteroidal anti-inflammatory drugs, including sodium salicylate, inhibit extracellular bacterial biofilm production. The authors studied the effect of the addition of sodium salicylate on bacterial adherence and biofilm formation on contact lenses and cases and commonly used medical polymers. The study was done in vitro with bacterial adherence and biofilm measured on lenses and cases that were exposed to saline contaminated with Staphylococcus epidermidis and Pseudomonas aeruginosa with and without 1 and 3 mm sodium salicylate. Bacterial adherence to contact lenses was quantitated by a vortex assay and by scanning electron microscopy. Biofilm formation on contact lens cases and other polymers was measured by an optical density assay and a radiolabeling assay. Inhibition of biofilm formation was demonstrated on plastic contact lens cases in a dose-related manner with 1 and 3 mm sodium salicylate. A dose-related decrease in bacterial adherence also was noted. Assays with contact lenses also demonstrated less adherence in the presence of sodium salicylate. Electron micrographs of the contact lens showed less biofilm, most noticeable with 3 mm salicylate. Other studies demonstrated decreased adherence of S. epidermidis to polyethylene and polystyrene. Sodium salicylate also decreased biofilm on plastic tissue culture wells, but sorbic acid paradoxically increased deposition. The authors found that the addition of low-dose sodium salicylate to saline decreased the adherence of S. epidermidis and P. aeruginosa to contact lenses and lens cases. Biofilm production also was decreased on the lens cases and on medical polymers used to make plastic cases. These studies suggest that sodium salicylate deserves additional study to determine its use in contact lens solutions.