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Published on: April 9, 2013
Evaluation of Protamine as a Disinfectant for Contact Lenses
Mahesh K Bandara1, Simin Masoudi, Hua Zhu
1*PhD †BSc ‡PhD, FAAO Brien Holden Vision Institute (MKB, SM, HZ, RB), and School of Optometry and Vision Science (SM, HZ, RB, MDPW), University of New South Wales, Sydney, New South Wales, Australia.
Purpose:
To investigate the ability of protamine, alone or in combination with other antimicrobial agents, to kill bacteria and fungi associated with contact lens-related keratitis.
Methods:
The International Organization for Standardization 14729:2001 procedure was used to test the antimicrobial activity of solutions of protamine (23-228 μM) with and without polyhexamethylene biguanide (PHMB) and ethylenediamine tetra-acetic acid (EDTA). The recommended ISO panel of microbes along with six clinical isolates was tested. The effect of increasing sodium chloride concentration on the antimicrobial activity was also assessed. The cytotoxicity of the final protamine/EDTA/PHMB solution was measured using ISO 10993-5 standard assays.
Results:
Protamine gave a dose-dependent antimicrobial effect, with the highest effect for most strains being at 228 μM (≥6 log reductions of viable bacteria and ≥1 log reduction of viable fungi). Addition of EDTA and PHMB increased the antimicrobial effect for all strains except Pseudomonas aeruginosa ATCC6538, which had optimum activity (≥6 log inhibition) even in protamine alone. The optimum antimicrobial activity of all microbes was achieved in 0.2% sodium chloride, but even in 0.8% sodium chloride, the activity met or exceeded the ISO standard (>3 log reductions for bacteria and >1 log reduction for fungi). None of the formulations was cytotoxic to mammalian cells.
Conclusions:
This study highlights the potential for protamine to be used for the development of effective multipurpose disinfection solutions. Further investigations such as stability, compatibility with contact lenses, and in vivo toxicity are warranted.
Insights
Protamine demonstrates dose-dependent antimicrobial properties against contact lens-related keratitis pathogens. Combined with PHMB and EDTA, it offers a promising, non-cytotoxic base for multipurpose disinfection solutions.
Area of Science:
- Microbiology and Infectious Diseases
- Ophthalmology
- Biomaterials Science
Background:
- Contact lens-related keratitis poses a significant risk to ocular health.
- Effective antimicrobial agents are crucial for contact lens care and preventing microbial infections.
- Current disinfection solutions require continuous innovation to combat resistant microbial strains.
Purpose of the Study:
- To evaluate the antimicrobial efficacy of protamine, alone and in combination with polyhexamethylene biguanide (PHMB) and ethylenediamine tetra-acetic acid (EDTA).
- To assess the potential of protamine-based formulations for contact lens disinfection solutions.
- To determine the cytotoxicity of protamine-based formulations on mammalian cells.
Main Methods:
- Antimicrobial activity was tested using the International Organization for Standardization (ISO) 14729:2001 procedure.
- Protamine solutions (23-228 μM) with and without PHMB and EDTA were tested against a panel of bacteria and fungi.
- Cytotoxicity was evaluated using ISO 10993-5 standard assays.
Main Results:
- Protamine exhibited dose-dependent antimicrobial activity, with significant log reductions in viable bacteria and fungi at 228 μM.
- The addition of EDTA and PHMB enhanced antimicrobial effects for most tested microbes.
- Optimal antimicrobial activity was observed at 0.2% sodium chloride concentration, meeting ISO standards even at 0.8% sodium chloride.
- Protamine/EDTA/PHMB formulations showed no cytotoxicity to mammalian cells.
Conclusions:
- Protamine shows considerable potential as a key component in developing effective multipurpose contact lens disinfection solutions.
- Further research is recommended to explore protamine's stability, compatibility with contact lenses, and in vivo toxicity.
- These findings suggest a promising avenue for novel antimicrobial strategies in contact lens care.
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