A comparison of the ability of three common contact lens solutions with different constituents to inhibit growth of Staphylococcus aureus

Abstract

Background: Staphylococcus aureus is a common commensal on skin and mucosal surfaces; its contact with the eye may cause a variety of ocular inflammations and infections such as blepharitis, conjunctivitis and keratitis, amongst others. Soft contact lenses provide perfect conditions for the breeding of certain pathogens, and disinfecting solutions for contact lenses are therefore of utmost importance. These solutions should be effective in inhibiting the growth of a variety of pathogens to protect the user from ocular infections.Aim: To highlight the need for clinicians to be aware of the effects of various recommended disinfecting contact lens solutions.Method: Three popular disinfecting contact lens solutions readily available in South Africa were chosen. These and a control solution (saline) were prepared and inoculated with S. aureus to evaluate the antimicrobial efficacy of each solution. The primary stand-alone test was used to evaluate the solutions according to the ISO standard specifically for this purpose.Results: The test results indicated that two of the solutions met the ISO standards; the third failed. Of the two that passed the test, only one showed the required 3-log reduction after 30 minutes, as per the ISO standard, although this solution is marketed as a ’10 minute system’.Conclusion: It is important for clinicians to be aware of the complications that may be caused by contaminated solutions, and patients should be warned about the effects thereof. To ensure healthy eyes for our patients, sufficient knowledge regarding the efficacy of recommended multipurpose solutions is necessary. Solutions that meet ISO standards promote good ocular health and ensure sufficient cleaning and disinfecting of contact lenses.