The Antimicrobial Efficacy of Multipurpose Contact Lens Solutions on Standard Strains of Common Ocular Pathogens

Abstract

Objective: To compare the antimicrobial effects of locally available multipurpose contact lens solutions (MPS) on the growth of standard strains of contact lens-related ocular pathogens and to establish the recommended duration of exposure to these solutions to achieve maximal antimicrobial efficacy. Methods: This study, a single-blind controlled experiment, evaluated five locally available MPS in terms of their antimicrobial efficacy towards common contact lens-related ocular pathogens, such as P. aeroginosa, S. aureus, E. coli, F. solani, and C. albicans, using the stand alone criteria. Microbial viability counts were obtained at serial durations: after 1 hour, 3 hours, 6 hours, and 12 hours of exposure. Results: MPS containing polyquaternium-1 and myristamidopropyl dimethylamine (MAPD) and polyhexamide reduced the bacterial concentrations by 3 log and fungal concentrations by 1 log, enabling them to fulfill the stand alone criteria for disinfecting solutions as mandated by ISO/CD 14729. This antimicrobial efficacy was most evident at 6 hours of exposure to the challenge organisms. MPS containing polyquaternium-1 and MAPD also have the broadest spectrum of effectivity against gram-negative and gram-positive bacteria, and C. albicans. All MPS tested have poor microbial activity against F. solani. Conclusion: Multipurpose contact lens solutions demonstrated variability in their antimicrobial activity. MPS with broad spectrum efficacy and effectivity, such as those containing polyquaternum and MAPD, are preferred to prevent contact lens-related ocular infections.

Keywords

• contact
• multipurpose contact lens solutions
• microbial keratitis
• infectious keratitis
• silicon hydrogels