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Effect of lysozyme on adhesion and toxin release by Staphylococcus aureus
A Thakur1, A Chauhan, M D Willcox
1Cornea and Contact Lens Research Unit, Cooperative Research Centre for Eye Research and Technology, University of New South Wales, Sydney, Australia. a.thakur@cclru.unsw.edu.au
Purpose:
Staphylococcus aureus is a common cause of ocular infection and inflammation. We hypothesized that potential for S. aureus to cause an ocular infection would be enhanced if these bacteria are able to adhere to the biomaterials used in contact lenses. In turn, bacterial adhesion could also be influenced by other factors, such as properties of contact lenses and the absorbance of some tear components. We investigated the effect of the tear protein lysozyme on S. aureus adhesion to contact lenses and its effect on production of toxins or enzymes.
Methods:
Bacterial adhesion on contact lenses was determined by counting the total number of bacteria as well as viable bacteria on lysozyme-coated or non-coated lenses, and by counting bacteria grown in the presence or absence of lysozyme in the medium. Toxin and enzyme production was assessed by haemolysis and proteolysis assays.
Results:
Our results indicate that adhesion was significantly increased in the presence of lysozyme, both in the medium and coated onto contact lenses (P=0.04). The presence of lysozyme did not alter the production of alpha- or beta- toxins. However, the presence of lysozyme inhibited elastase activity.
Conclusion:
These results indicate that lysozyme deposition on contact lenses promoted S. aureus adhesion. The tear protein lysozyme might modify elastase activity and thus modulate the production of corneal degradation resulting from the action of this enzyme.