Different contact lens case treatment methods for the elimination of pathogen biofilms associated with contact lens related microbial keratitis / 中华实验眼科杂志

Objective:To investigate the biofilm-forming abilities of pathogens associated with contact lens related microbial keratitis and to compare the efficacies of different treatments in eliminating biofilms in contact lens cases (CLCs).Methods:Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Candida albicans biolm formation in polypropylene CLCs was examined by using a static biofilm formation model, which was incubated at 37 ℃ for 24 hours.According to the CLC treatment methods, the experimental groups were divided into a control group, a room temperature air-drying group, a contact lens care solution soaking group, a heat-drying group and a soaking-heating group.A pathogen colony counting-based serial dilution micro-counting method was applied to evaluate the biofilm elimination efficacies and pathogen killing rates of treatments.Results:All four tested strains formed biofilms on the inner walls of the CLC, and the biomasses of S. aureus, P. aeruginosa, E.coli and C. albicans biofilm were (10.78±2.12), (9.19±0.57), (8.03±0.30), and (7.50±0.07)lg CFU/ml, respectively.The S. aureus biofilm biomass was significantly higher than those of the other strains (P<0.05). The biofilm biomasses of all the tested strains in the heat-drying and the soaking-heating groups were significantly lower than those in the control group (all at P<0.05); and the biofilm biomasses of S. aureus and E. coli in the soaking group were significantly lower than that in the control group (all at P<0.05). The heat-drying treatment resulted in a killing rate of (51.76±16.75)% for S. aureus, (68.63±4.43)% for P. aeruginosa, (83.51±13.97)% for E. coli, and (97.13±5.19)% for C. albicans, respectively (F=31.806, P<0.001). Significant differences were observed between the killing rates for each bacterium (all at P<0.05). The E. coli and C. albicans killing rates of the soak-heating treatment were (100.00±0.00) % and (97.79±7.67)%, respectively, and were significantly higher than (81.13±14.86)% of S. aureus and (74.22±11.91)% of P. aeruginosa (all at P<0.05).Conclusions:Heating alone or combined with the use of contact lens care solution treatment can improve the pathogen killing rates and effectively eliminate the bacterial and fungal contaminations in CLCs.