Poor Contact Lens Hygiene Behaviors
Poor Contact Lens Hygiene Behaviors
Purpose: The aim of this study was to simulate the biofilm formation in contact lens (CL) case under poor hygiene behaviors; antimicrobial efficacies of multipurpose solutions (MPSs) against biofilm on the lens case were evaluated.
Methods: Five MPSs (Epica Cold, Complete 10 min, ReNu MultiPlus, SoftOne Mois, and OPTI-FREE Plus) were tested. Lens cases containing ACUVUE2 were inoculated with 1×10, 10, or 10 colony-forming units (CFUs) of Staphylococcus epidermidis (SE). Each lens case was treated with 1 MPS for 4 hrs followed by the estimation of the number of SE by the CFU method. Disinfection efficacies of MPSs against SE biofilm were evaluated by biomicroscopy with safranin staining and scanning electron microscopy.
Results: Lens cases, inoculated with 1×10 CFU, were disinfected by all MPSs. Epica Cold, Complete 10 min, ReNu MultiPlus, and OPTI-FREE showed almost a 2-log reduction of the CFU, whereas SoftOne Mois effect was almost a 1 log reduction, significantly lower than other MPSs (P<0.05). No biofilm formations were observed in Epica Cold, Complete 10 min, ReNu MultiPlus, and OPTI-FREE Plus-treated groups unlike significant biofilm formation in the SoftOne Mois-treated group (P<0.01).
Conclusions: Greater efforts to educate patients regarding compliant lens care behavior are needed to reduce the incidence of CL-associated microbial keratitis.
Recently, an outbreak of Fusarium keratitis, a rare fungal infection, has been linked to contact lens (CL) wear in Singapore, Hong Kong, and the United States. This fungal epidemic among CL wearers strongly implicated one specific multipurpose solution (MPS), ReNu with Moisture Loc. This outbreak is believed to be caused by insufficient antimicrobial efficacy of this MPS against Fusarium solani (FS) after evaporation. Furthermore, Verani, a researcher at the Center for Disease Control has presented in the Food and Drug Administration panel meeting in 2008 that noncompliant lens care behaviors such as "topping off" or reuse of MPS caused a 4.4-fold higher risk of microbial keratitis. These findings clearly showed a direct correlation between SCL-related microbial keratitis and noncompliant lens care behaviors.
On the other hand, it is well known that "biofilm," extracellular sugar–protein secreted by bacteria, increases the affinity of bacterial colonies to biomaterial surfaces and also enhances the tolerance to antibiotics 1,000 times higher than their planktonic cells. It was also suggested that biofilm formation of infectious bacteria may be associated with high incidence of microbial keratitis. Investigations over the last two decades have shown that mechanical rubbing and subsequent rinsing of CL are two important key elements to prevent biofilm formation on the surface of CL and lens storage cases. For example, Sutton et al. demonstrated that a combination of mechanical rubbing and rinsing of CL reduced the level of biofilm to 10 to 10 using the multiitem microbial challenge test in vitro.
Pseudomonas aeruginosa (PA) and coagulase-negative Staphylococci (CNS) have been historically associated with soft CL (SCL)-related infection keratitis. Among these microorganisms, Staphylococcus epidermidis (SE), a typical CNS, is known to be the highest biofilm producer. Wu et al. reported that CNS was the most frequently recovered microorganisms contaminated in CL storage cases. In addition, the intercellular adhesion genes icaA has been shown to be expressed only in biofilm-forming SE strains. Suzuki et al. have shown that icaA gene expression was 60% higher in the conjunctiva-isolated SE compared with facial skin-isolated SE. In view of these findings, it is believed that conjunctiva-isolated SE might be responsible for bacterial keratitis seen among CL wearers.
In this study, we investigated the efficacy of five commercially available MPSs in simulated poor lens care behaviors using three test methods. First, antimicrobial efficacies of test MPSs against SE strain, a model microorganism forming biofilm, at three different inoculation size were evaluated in a lens storage case containing an SCL. Second, the formation of SE biofilm in lens storage cases containing an SCL was evaluated after the cycle treatment with test MPS. Third, the breakdown of SE biofilm treated with test MPS was observed with scanning electron microscopy (SEM).
Abstract and Introduction
Abstract
Purpose: The aim of this study was to simulate the biofilm formation in contact lens (CL) case under poor hygiene behaviors; antimicrobial efficacies of multipurpose solutions (MPSs) against biofilm on the lens case were evaluated.
Methods: Five MPSs (Epica Cold, Complete 10 min, ReNu MultiPlus, SoftOne Mois, and OPTI-FREE Plus) were tested. Lens cases containing ACUVUE2 were inoculated with 1×10, 10, or 10 colony-forming units (CFUs) of Staphylococcus epidermidis (SE). Each lens case was treated with 1 MPS for 4 hrs followed by the estimation of the number of SE by the CFU method. Disinfection efficacies of MPSs against SE biofilm were evaluated by biomicroscopy with safranin staining and scanning electron microscopy.
Results: Lens cases, inoculated with 1×10 CFU, were disinfected by all MPSs. Epica Cold, Complete 10 min, ReNu MultiPlus, and OPTI-FREE showed almost a 2-log reduction of the CFU, whereas SoftOne Mois effect was almost a 1 log reduction, significantly lower than other MPSs (P<0.05). No biofilm formations were observed in Epica Cold, Complete 10 min, ReNu MultiPlus, and OPTI-FREE Plus-treated groups unlike significant biofilm formation in the SoftOne Mois-treated group (P<0.01).
Conclusions: Greater efforts to educate patients regarding compliant lens care behavior are needed to reduce the incidence of CL-associated microbial keratitis.
Introduction
Recently, an outbreak of Fusarium keratitis, a rare fungal infection, has been linked to contact lens (CL) wear in Singapore, Hong Kong, and the United States. This fungal epidemic among CL wearers strongly implicated one specific multipurpose solution (MPS), ReNu with Moisture Loc. This outbreak is believed to be caused by insufficient antimicrobial efficacy of this MPS against Fusarium solani (FS) after evaporation. Furthermore, Verani, a researcher at the Center for Disease Control has presented in the Food and Drug Administration panel meeting in 2008 that noncompliant lens care behaviors such as "topping off" or reuse of MPS caused a 4.4-fold higher risk of microbial keratitis. These findings clearly showed a direct correlation between SCL-related microbial keratitis and noncompliant lens care behaviors.
On the other hand, it is well known that "biofilm," extracellular sugar–protein secreted by bacteria, increases the affinity of bacterial colonies to biomaterial surfaces and also enhances the tolerance to antibiotics 1,000 times higher than their planktonic cells. It was also suggested that biofilm formation of infectious bacteria may be associated with high incidence of microbial keratitis. Investigations over the last two decades have shown that mechanical rubbing and subsequent rinsing of CL are two important key elements to prevent biofilm formation on the surface of CL and lens storage cases. For example, Sutton et al. demonstrated that a combination of mechanical rubbing and rinsing of CL reduced the level of biofilm to 10 to 10 using the multiitem microbial challenge test in vitro.
Pseudomonas aeruginosa (PA) and coagulase-negative Staphylococci (CNS) have been historically associated with soft CL (SCL)-related infection keratitis. Among these microorganisms, Staphylococcus epidermidis (SE), a typical CNS, is known to be the highest biofilm producer. Wu et al. reported that CNS was the most frequently recovered microorganisms contaminated in CL storage cases. In addition, the intercellular adhesion genes icaA has been shown to be expressed only in biofilm-forming SE strains. Suzuki et al. have shown that icaA gene expression was 60% higher in the conjunctiva-isolated SE compared with facial skin-isolated SE. In view of these findings, it is believed that conjunctiva-isolated SE might be responsible for bacterial keratitis seen among CL wearers.
In this study, we investigated the efficacy of five commercially available MPSs in simulated poor lens care behaviors using three test methods. First, antimicrobial efficacies of test MPSs against SE strain, a model microorganism forming biofilm, at three different inoculation size were evaluated in a lens storage case containing an SCL. Second, the formation of SE biofilm in lens storage cases containing an SCL was evaluated after the cycle treatment with test MPS. Third, the breakdown of SE biofilm treated with test MPS was observed with scanning electron microscopy (SEM).
Source...