Activity of multipurpose contact lens solutions against Staphylococcus aureus, Pseudomonas aeruginosa, Serratia marcescens and Candida albicans biofilms.

Introduction: The use of contact lenses has progressively increased around the world, thereby increasing the risk of complications. The most serious complication is microbial keratitis (corneal infection) that can progress to a corneal ulcer.
Methods: Fourteen multipurpose contact lens solutions were tested on mature biofilms comprising Staphylococcus aureus, Pseudomonas aeruginosa, Serratia marcescens and Candida albicans, using the minimum disinfection times recommended by the manufacturers. The biofilm was induced in the lens case, and 24 h later, the solutions were added. Activity against planktonic and sessile cells was evaluated and quantified as colony forming units per millilitre. The minimum concentration for biofilm eradication was defined as a 99.9% reduction in viable cells.
Results: Although most solutions exhibited activity against planktonic cells, only five of the 14 solutions produced a significant reduction in the S. marcescens biofilm. No solution achieved the minimal biofilm eradication of S. aureus, P. aeruginosa and C. albicans.
Conclusion: Multipurpose contact lens solutions provide greater bactericidal and/or fungicidal activity on planktonic cells than biofilms. The minimal eradication biofilm concentration was only achieved for S. marcescens.
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