Antimicrobial efficacy of contact lens solutions against pseudomonas aeruginosa and staphylococcus aureus

Abstract

Contact lenses are used as an alternative to eyeglasses for correction of eyesight problems such as myopia, hyperopia and astigmatism. However, contact lenses wearers, especially extended wearers, are at risk for bacterial keratitis. Staphylococcus aureus and Pseudomonas aeruginosa are the most common pathogens causing bacterial keratitis. To minimize the risk of eye infections, contact lens care solutions were used in order to decrease the amount of potential pathogens during contact lens storage. The purpose of this study was to evaluate the antimicrobial activity of multipurpose contact lens care solutions available in Thailand against the common causes of bacterial keratitis, Pseudomonas aeruginosa and Staphylococcus aureus. Four multipurpose contact lens care solutions, designed as A, B, C and D, were determined for antimicrobial activities against methicillin-resistant Staphylococcus aureus (MRSA) ATCC43300, methicillin-sensitive Staphylococcus aureus (MSSA) ATCC25930 and Pseudomonas aeruginosa ATCC2785 by agar-well diffusion method. Minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were also determined. In addition, the contact time between test bacteria and each contact lens care solution was determined for the effective duration time that can reduce 99.9% (3logs) of test bacteria. The results showed that all test contact lens care solutions did not show inhibition zone when tested with methicillin-resistant Staphylococcus aureus (MRSA) ATCC43300, methicillin-sensitive S. aureus (MSSA) ATCC25930 and Pseudomonas aeruginosa ATCC2785 by agar-well diffusion method diffusion. However, the test contact lens care solutions at the concentration ranging between 12.5-25% of the initial concentration inhibited the growth of all test bacteria. This study also revealed that contact lens care solution D has more killing effect than contact lens care solution A, B and C since it can reduce the number of test bacteria more than 99.9% (3logs) in 2 hours. The different in killing effect might be due to the difference in active ingredients in each solutions. Therefore, the information from this study may be helpful for formulation of contact lens care solutions with more potent antibacterial activity.