Biocidal Efficacies of Contact Lens Disinfecting Solutions Against Gram-Negative Organisms Associated with Lens Case-Associated Corneal Infiltrative Events.

Background: Multi-purpose solutions (MPSs) are designed to clean, disinfect, and condition contact lenses (CLs) to reduce the risk of contact lens-related adverse events, such as corneal infiltrative events (CIEs) that are often associated with opportunistic bacteria from contaminated CLs or CL cases. This study evaluated the disinfection efficacies of six MPSs and one hydrogen peroxide solution (HPS) comparator against three lens case CIE-associated organisms.

Methods: The solutions in this study were evaluated against commonly isolated Gram-negative lens case CIE-associated organisms in the presence of organic soil, according to the International Organization for Standardization 14729 (ISO) stand-alone test protocol. Challenge organisms (Achromobacter xylosoxidans, Delftia acidovorans and Stenotrophomonas maltophilia) were inoculated into the solutions in conical tubes (for MPS) or CL cases (for HPS), and plated for organism quantification after the manufacturer-recommended minimum soak times. Disinfection efficacy for each solution is presented as mean log reduction per organism and overall disinfection across three challenge organisms (post hoc analysis).

Results: Stand-alone testing against the challenge organisms demonstrated that PAPB/Alexidine/PQ-1, Alexidine/PQ-1, and PHMB-containing MPSs, as well as HPS were significantly superior versus MAPD/PQ-1-based MPSs (all p < 0.05). While there is no ISO criteria for reduction of CIE-associated organisms, all solutions containing PAPB/Alexidine/PQ-1, Alexidine/PQ-1, and PHMB, as well as HPS, achieved greater than 3-log reductions (the primary criteria for ISO 14729 compendial bacterial organisms) for all challenge organisms. The three MAPD/PQ-1-containing MPSs achieved between 0.6 and 1.7 log reduction across the MPS/test organism combinations.

Conclusion: The PAPB, PHMB, and Alexidine-based MPSs demonstrated significantly greater disinfection efficacy than MAPD-based MPSs, and comparable disinfection efficacy to HPS, against commonly isolated Gram-negative CL case CIE-associated organisms.