Antimicrobial Efficacy of Contact Lens Care Solutions Against Neutrophil-Enhanced Bacterial Biofilms

PURPOSE Neutrophil-derived extracellular debris has been shown to accelerate bacterial biofilm formation on hydrogel and silicone hydrogel contact lens surfaces compared to lenses inoculated with bacteria alone. The purpose of this study was to evaluate the disinfection efficacy of four standard commercial contact lens cleaning regimens against neutrophil-enhanced bacterial biofilms formed on silicone hydrogel contact lenses. METHODS Four reference strains were used: Pseudomonas aeruginosa, Serratia marcescens, Stenotrophomonas maltophilia, and Staphylococcus aureus. Human neutrophils were isolated from peripheral blood by venipuncture. Unworn Lotrafilcon B lenses were incubated overnight in each respective strain with stimulated neutrophils. Contact lenses were then cleaned using one of four contact lens care solutions according to manufacturer instructions. Bacterial viability was assessed by colony counts and confocal microscopy. Volume of residual debris on lens surfaces after cleaning was quantified using IMARIS software. RESULTS All four solutions tested showed effective antimicrobial activity against each bacterial strain; however, substantial amounts of nonviable bacteria and cellular debris remained on the lens surface despite concomitant digital cleaning. CONCLUSIONS Necrotic cellular debris that accumulates under the posterior lens surface during wear of an inoculated contact lens is not fully removed during routine cleaning and disinfection. TRANSLATIONAL RELEVANCE The accumulation of residual cellular debris on the contact lens surface may contribute to new colonization of the lens and represents a significant risk factor for a contact lens-related adverse event. Additional studies are needed to correlate these findings with risk for corneal infiltrative and/or infectious events in a standard animal model.