The role of Pseudomonas aeruginosa biofilm in the attachment of Acanthamoeba to four types of hydrogel contact lens materials

Purpose. The effect of the previous coating of a contact lens surface with Pseudomonas biofilm on adsorption of Acanthamoeba onto four types of hydrogel materials was investigated. Methods. Hydrogel contact lens quarters from each of the four FDA groups of hydrogel materials were incubated for at least 12 h in a suspension of 10(7)/ml of Pseudomonas aeroginosa (ATCC 27853) to coat their surfaces with biofilm, After rinsing, the lenses were incubated for 90 min in 5 x 10(5)/ml of Acanthamoeba castellanii trophozoites, New, uncoated lens quarters were incubated in the Acanthamoeba suspension as controls. After rinsing, all adsorbed trophozoites on one surface of each lens quarter were counted by direct light microscopy, Adsorption was expressed as numbers of amoebae per square centimeter of lens surface, and nonparametric data analysis was performed. Results. Acanthamoeba adsorption to new, uncoated lenses was greater for ionic materials (groups 3 and 4) than for the nonionic materials (groups 1 and 2), Pseudomonas biofilm increased adsorption on all four lens types, Conclusion, Pseudomonas biofilm enhanced adsorption of Acanthamoeba on all lens types studied, but the adsorption to nonionic materials was significantly less, This suggests that all lens wearers may be at increased risk for Acanthamoeba infection if lenses are previously contaminated with bacterial biofilm, but this risk may be reduced by the use of certain lens types (low water content, nonionic materials).