Evaluation of contact lens multipurpose solutions on bacterial biofilm development

Objectives: No sooner are contact lenses (CLs) inserted into the eyes, than lipids, proteins and glycoproteins rapidly accumulate on their surface thus favouring the adhesion of commensal bacteria and biofilm formation. Infections may be caused by the proliferation of indigenous flora or other opportunistic pathogens. Our purpose was to evaluate the activity and the capacity of different CL solutions to interfere with the mechanisms of biofilm formation and stability, and use of a system to study dynamically biofilm development. Methods: We evaluated the anti-biofilm activity of three different multipurpose solutions (MPSs): Regard®, BiotrueTM and OPTI-FREE® PureMoist® on four bacterial species (Serratia marcescens and Pseudomonas aeruginosa, Staphylococcus epidermidis and Staphylococcus aureus). Static biofilm assay was first performed to analyse the effect of MPSs. Dynamic assays were performed with the BioFlux system to analyse the effect of the OxyChlorite® solution Regard® on the biofilm formation. Results: Our studies show that MPSs are able to completely inhibit biofilm formation of Staphylococcus species and of S. marcescens after only 4 h of incubation. Moreover a reduction of biofilm formation by Pseudomonas was noted. Best results on P. aeruginosa were obtained with Regard®. Regard® was also used for dynamic assay revealing its ability to disaggregate the mature biofilm. Regard® completely inhibited biofilm formation by S. epidermidis and slowed down biofilm development by P. aeruginosa. Conclusions: Our findings indicate that the CL solutions tested were all able to reduce biofilm formation. Furthermore, the BioFlux system was proven to be useful for the evaluation of the effectiveness of CL solutions against microbial biofilm formation.