Differential bacterial colonization and biofilm formation on punctal occluders in vitro.

Abstract

Purpose : Dry eye is a common condition treated primarily by topical lubricants, immunomodulation, and punctal and canalicular plugs (occluders). Biofilm formation has been reported in the literature as an ongoing problem with the clinical use of occluders. In order to explore the role of biofilm formation on occluders, we tested two strains of bacteria, Pseudomonas aeruginosa and Staphylococcus aureus, with three different types of occluders, Comfortear^R, Parasol^R and Quintess^R.

Methods : Each occluder type was incubated in nutrient broth containing P. aeruginosa and S. aureus for 7 days. They were then removed, centrifuged, and stained with 0.1% crystal violet. The same staining procedure was done with unused occluders. The eluted crystal violet from each occluder (both experimental and unused control) was measured in a spectrophotometer at an optical density (OD) of 600nm. The OD of the control samples were subtracted from the experimental values before the data was plotted. Each occluder type was tested in triplicate. The results are presented as group mean +/- standard deviation (SD). Significance of the results was determined using the Kruskal–Wallis nonparametric ANOVA for multiple comparisons. These quantitative results were verified with scanning electron microscopy (SEM).

Results : Surface smoothness was more regular on the Parasol^R punctal occluder. With exposure to P. aeruginosa, no quantitative difference was noted in the amount of bacterial colonization between the three occluders. In contrast, with exposure to S. aureus, a ~3 fold statistically significant difference in bacteria colonization between the Parasol^R and Quintess^R occluder and a ~2 fold higher trend between Parasol^R and Comfortear^R occluder were detected. SEM showed extensive S. aureus biofilm formation on the Parasol^R occluder.

Conclusions : The results indicate that bacterial colonization readily occurs on all three types of occluders with S. aureus. The occluder with the smoothest surface (Parasol^R) displayed increased biofilm formation when compared to those with rougher surfaces.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

 

Occluders. Scale in mm.

 

Occluder surface morphology imaged with SEM. (A, D) Comfortear; (B, E) Parasol; (C, F) Quintess. Arrow heads: biofilm observed on Parasol. White arrows: S. aureus cells. Black arrows: biofilm. White boxes in A, B and C are areas magnified and shown in D, E and F. Scale bar for A, B, C = 100mm; Scale bar for D, E, F = 1mm.