Debarun Dutta is a research associate at the School of Optometry and Vision Science, University of New South Wales. Download the poster (.pdf), which was originally shared at the Annual Meeting of The Association for Research in Vision and Opthalmology (ARVO), 2014.
Purpose: There remains a need to reduce microbial contamination of contact lenses, and thus the rate of adverse events during wear. The purpose of the current study was to characterise and evaluate antimicrobial efficacy of a short synthetic cationic peptide, MEL4, against Pseudomonas aeruginosa and Staphylococcus aureus.
Methods: Mel4 (K-N-K-R-K-R-R-R-R-R-R-G-G-R-R-R-R) is a shorter version of the cationic peptide melimine, and was covalently incorporated into etafilcon A contact lenses. The amount of peptide present on the lens surface was quantified using X-ray photoelectron spectroscopy (XPS) and the total amount of peptide by amino acid analysis (AAA). In vitro cytotoxicity was determined using direct contact on murine L929 cells. Antimicrobial activity against the P. aeruginosa strains 6204 and ATCC 9027, and S. aureus strains 31 and 38 was evaluated by measuring the amount of cell death compared to control lenses with no Mel4 (measured as change in log colony forming units [cfu] per lens).
Results: AAA revealed that 111.6±0.32 μg of Mel-4 was attached to lenses. XPS showed increased presence of amide nitrogen (0.73%) at the lens surface compared to uncoated controls (<0.01%) confirming the presence of Mel4. The peptide attached contact lenses were not associated with any in vitro cytotoxicity. Activity against P. aeruginosa strains 6204 and ATCC 9027 was reductions of 1.0±0.3 log cfu and 1.6±0.3 log cfu respectively. Activity against S. aureus strain 31 and 38 was reductions of 1.0±0.1 log cfu, and 1.9±0.3 log cfu respectively.
Conclusions: Mel4 cationic peptide is not cytotoxic to mammalian cells in vitro and may offer excellent potential for development as an antimicrobial coating for contact lenses, showing high activity against both Gram negative and Gram positive bacteria.
