Abstract
Purpose: :
To investigate the antimicrobial and cleaning properties of a test H2O2 contact lens disinfecting system designed to prevent microbial growth after neutralization for extended time.
Methods: :
The antimicrobial efficacy of the test solution was evaluated against Acanthamoeba castellanii, A. Polyphaga, Staphylococcus aureus, Pseudomonas aeruginosa, Serratia marcescens, Candida albicans, Aspergillus niger and Fusarium solani. Conventional and novel microbiological test included Stand-alone, Contact Lens Disinfection studies (Regimen), Preservative Efficacy Testing (PET), Stasis studies, Encystment studies as well as the newly designed Latency studies. Lysozyme cleaning efficacy of the test solution and two H2O2 solution controls (ClearCare® and Oxysept®) was assessed on Acuvue® 2 lenses.
Results: :
After six hours of disinfection time, the new test solution showed more than 2 log kill against cysts of A. castellanii and A. polyphaga and caused no Encystment (<1%) for the trophozoites of these species. Stand-alone studies showed more than 12 log "combined" reductions for all three bacteria and more than 6 log "combined" reductions for both fungi. The regimen results for bacterial, fungal and Acanthamoeba spp. showed <10 cfu/lens after soaking for six hours in this new solution after application of the recommended cleaning steps. The results of Latency studies showed no growth after neutralization cycle for up to 35 days in the basket lens cases after a re-challenge at day 7. Lysozyme cleaning efficacy of the test solution was 18.0 ± 6.2% which was statistically lower than that of ClearCare® (32.7± 5.0%), but statistically greater than that of Oxysept® (10.0 ± 3.6%).
Conclusions: :
In addition to the H2O2 test solution possessing antibacterial, antifungal and antiamoebal properties, we have demonstrated it to possess latency properties through various microbiological methodologies. Lysozyme cleaning efficacy was also demonstrated, which in the absence of surfactant was shown to function through an ion-exchange mechanism.
Keywords: Acanthamoeba • contact lens • Staphylococcus