A comparison of the use of an ATP-based bioluminescent assay and image analysis for the assessment of bacterial adhesion to standard HEMA and biomimetic soft contact lenses

The aim of this study was to investigate in vitro adhesion of clinically re levant bacteria to standard HEMA and novel biomimetic soft contact lenses ( SCL) using bioluminescent ATP assay and image analysis. Unworn SCL were inc ubated with Pseudomonas aeruginosa, Staphylococcus epidermidis or Serratia marcescens suspended in sterile phosphate buffered saline (PBS). The level of bacterial adhesion after 1, 2, 4, 6 and 18 h, was assessed using both im age analysis and a bioluminescent ATP assay. Species differences in the ove rall level of adhesion to the different types of lens were observed using b oth measurement techniques. Generally bacterial adhesion was shown to peak at 4-6 h, then decline to a much lower level by 18 h. After 4 h, adhesion o f all species of bacteria to the biomimetic SCL (omafilcon A) was found to be significantly lower than to the standard HEMA SCL (polymacon) (p < 0.05, Student's t-test, n = 4). Both these techniques demonstrated that novel bi omimetic SCL materials exhibit significantly lower bacterial adhesion in vi tro compared to standard HEMA SCL materials. SCL manufactured with these no vel biomimetic materials may reduce the risk of infection. (C) 2001 Elsevie r Science Ltd. All rights reserved.