The influence of lens material and lens wear on the removal and viability of Staphylococcus epidermidis.
OBJECTIVE
The aim of this study was to evaluate the influence of lens material and lens wear on the removal capability of Staphylococcus epidermidis. Assessment of viability of remaining adhered bacteria was another goal of this work. Four silicone hydrogel materials (galyfilcon A, balafilcon A, lotrafilcon A, lotrafilcon B) and one conventional hydrogel material (etafilcon A) were assayed.


METHODS
Detachment studies on S. epidermidis were carried out in a parallel plate flow chamber. Contact lenses (CLs) were fitted to the bottom of the flow chamber and a bacterial suspension was perfused into the system, promoting bacterial adhesion. Afterwards, detachment was stimulated using a multipurpose solution (MPS, ReNu Multiplus) and the percentage of removed bacteria estimated through microscopic observation and enumeration. Remaining adhered bacteria were stained with propidium iodide (PI) and enumerated in order to assess their viability. Additionally, the worn lenses were observed by confocal laser scanning microscopy (CLSM) to visualize bacterial distribution along the lens surfaces.


RESULTS
Bacterial removal was significant (p<0.05) for both unworn and worn galyfilcon A and etafilcon A. Galyfilcon A exhibited a detachment percentage of 59.1 and 63.5 while etafilcon A of 62.6 and 69.3, both for unworn and worn lenses, respectively. As far as bacterial viability is concerned, it was found that worn lenses exhibit a superior amount of non-viable bacteria than unworn CLs. Images obtained by CLSM revealed an irregular bacterial distribution for all lens materials.


CONCLUSIONS
It appears that surface and/or bulk structure of the lens material affects removal of S. epidermidis while CL wear influences their viability.
Santos
Lívia
L
Institute for Biotechnology and Bioengenhary, Centre of Biological Engineering, University of Minho, Braga, Portugal.
Rodrigues
Diana
D
Lira
Madalena
M
Real Oliveira
M Elisabete C D
ME
Oliveira
Rosário
R
Vilar
Eva Yebra-Pimentel
EY
Azeredo
Joana
J
D000328:Adult; D001422:Bacterial Adhesion / Q000187:drug effects / Q000502:physiology*; D018639:Contact Lens Solutions / Q000494:pharmacology; D003263:Contact Lenses, Hydrophilic / Q000382:microbiology*; D005260:Female; D006801:Humans; D020100:Hydrogels; D008297:Male; D008689:Methacrylates; D018613:Microscopy, Confocal; D012828:Silicones; D013212:Staphylococcus epidermidis / Q000502:physiology*
D018639:Contact Lens Solutions; D020100:Hydrogels; D008689:Methacrylates; D012828:Silicones; C005044:hydroxyethyl methacrylate