Ozone against Pseudomonas aeruginosa biofilms in contact lenses storage cases

Pseudomonas aeruginosa is associated with ocular infections such as keratitis. Multipurpose contact lens solutions can be used for washing, disinfection and storage of contact lenses, however, P. aeruginosa biofilm disinfection by this method is unsatisfactory. The present study aimed to investigate the effectiveness of ozonated water in reducing P. aeruginosa colony count. Lenses kept in storage cases were contaminated with P. aeruginosa and disinfected using ozonized water, chlorhexidine, ultrasound and multipurpose solutions. The multipurpose solutions and ultrasound methods reduced colony count from 1.17 to 1.63 log10 CFU/cm2 (92.93% to 97.31%), respectively, of P. aeruginosa biofilm cell viability when compared to the positive control. Both, ozonated water and chlorhexidine showed 7.42 log reduction in the number of viable cells of P. aeruginosa biofilm. As compared to chlorhexidine, ozonized water did not depose any known toxic residues, so that we recommend it as an alternative disinfectant solution for contact lenses storage cases.