Abstract
Purpose: :
Protamine is a poly-cationic peptide found in the spermatic cells of different animal species. The purpose of this study was to evaluate the antimicrobial activity of protamine against ocular pathogens.
Methods: :
Antimicrobial performance of protamine with or without EDTA was evaluated according to stand-alone test for contact lens disinfection products described by the International Organization for Standardization (ISO) 14729. Staphylococcus aureus ATCC 6538, Pseudomonas aeruginosa ATCC 9027, Serratia marcescens ATCC 13880, Candida albicans ATCC 10231 and Fusarium solani ATCC 36031 were inoculated in phosphate buffered saline (PBS) containing 500 µg/ml of protamine with or without 0.05% EDTA, or PBS as a control. After disinfection at 25°C for 6 h, the numbers of viable microorganisms in the samples were determined and the average log reduction in test sample for each strain was calculated. Cytotoxicity of the protamine solution supplemented with 0.05% EDTA was examined in a cell growth inhibition assay by using murine cell lines (ATCC L-929) according to ISO 10993-5 standard.
Results: :
Protamine solution showed complete inhibition for P. aeruginosa and displayed 3.1 ± 0.5, 2.4 ± 0.75, 1.5 ± 0.01, and 1.0 ± 0.05 log reductions against S. aureus, S. marcecescens, C. albicans and F. solani respectively after 6 h of disinfection. The activity of protamine solution was enhanced by addition of 0.05% EDTA. Adding 0.05% EDTA to protamine increased the average log reduction units up to 4 against S. aureus, S. marcecescens. Further, the combination of protamine and EDTA also displayed 2.4 ± 0.41 and 1.8 ± 0.14 log-reductions for C. albicans and F. solani respectively. The cell growth inhibition assay showed no toxic effect of protamine/EDTA solutions.
Conclusions: :
The results have demonstrated that protamine is effective against all test micoorganisms and EDTA enhances the antimicrobial effectiveness of protamine. Thus these results suggest that combination of protamine and EDTA might be useful to develop effective and nontoxic disinfection solutions for soft contact lenses.
Keywords: contact lens • antibiotics/antifungals/antiparasitics • keratitis