To determine solution efficacy, lenses were washed with phosphate buffered saline (PBS) for at least five seconds and then placed in relevant solution for the manufacturer’s recommended duration. Biofilms were allowed to form on contact lenses for up to 24 hours and the number of colony forming units (CFU) on a contact lens for each species was determined at various time-points over 24 hours. Lotrafilcon A lenses were inoculated with the three bacterial species. Method of assessing contact lens care solution efficacy Complete MoisturePlus and ReNu with MoistureLoc were withdrawn from the market after study completion. The solutions contained either polyhexamethylene biguanide (PHMB) (ReNu MultiPlus, Bausch + Lomb, USA, Complete MoisturePlus, AMO, USA, AQuify, CIBA Vision, USA), alexidine (ReNu with MoistureLoc, Bausch + Lomb, USA), polyquaternium-1/myristamidopropyl dimethylamine (OPTI-FREE RepleniSH, ALCON, USA) or hydrogen peroxide (ClearCare, CIBA Vision, USA). Lotrafilcon A contact lenses were chosen as they represent a leading extended wear silicone hydrogel material while the lens care solutions chosen were the most commonly used at the time of the study. These species were selected as they are common causative agents of contact-lens associated inflammation and infection. Two Gram-negative ( Pseudomonas aeruginosa, Serratia marcescens) and one Gram-positive ( Staphylococcus aureus) bacteria were evaluated. Additionally, they assessed the antimicrobial activities of contact lens care solutions against bacterial cells grown under planktonic or biofilm conditions. Szczotka-Flynn and colleagues used a bacterial biofilm contact lens model to determine whether three different bacterial strains, commonly associated with contact lens keratitis and inflammation, can form biofilm on silicone hydrogel contact lenses. Increased resistance of contact lens-related bacterial biofilms to antimicrobial activity of soft contact lens care solutions. The following is a review of an article that determines the efficacy of contact lens solutions against three types of bacterial biofilm. Current testing involves demonstrating efficacy against planktonic or single-cells microbes, while efficacy against biofilms is not required. However, recent outbreaks of atypical microbial keratitis have sparked a rethink in terms of how solutions are tested before they become commercially-available. Before a solution is released onto the market, certain criteria need to be met in terms of their ability to kill these pathogens. Solutions contain antimicrobial agents, which kill various pathogens including Gram-negative and Gram-positive bacteria. One of the major functions of a contact lens care solution is to disinfect contact lenses to make them safe to wear. Daniel Tillia is a research optometrist at the Brien Holden Vision Institute, a part-time clinical supervisor at the School of Optometry and Vision Science, University of New South Wales, Australia and occasionally works in private practice
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