Factors affecting Staphylococcus epidermidis adhesion to contact lenses.
BACKGROUND
Staphylococcus epidermidis is a major causative agent of infectious keratitis associated with contact lens wear. Adhesion of this bacterium to contact lenses may contribute to the pathogenesis of infection and could be influenced by lens surface properties, packaging/storage solutions, and vary among different strains according to the level or type of adhesins expressed.


METHODS
Adhesion of six clinical isolates of S. epidermidis to three different contact lens materials was tested. Adhesion assays were performed on lenses immediately after removal from their packages, and also after lenses were soaked in sterile phosphate buffered saline (PBS) for 7 days to dilute the packaging solution.


RESULTS
For lenses tested immediately upon removal from their packaging, adhesion to polymacon (in PBS with 0.1% polyvinyl alcohol) was significantly greater than to etafilcon A (in borate buffered saline) and vifilcon A (in PBS). After soaking, adhesion to polymacon lenses was significantly less than to the other lens materials. This pattern was consistent for all strains, although major differences in baseline adhesion levels existed between strains, with exopolysaccharide (slime)-positive bacteria being more adherent to lenses.


CONCLUSIONS
Properties of contact lens materials were not the sole determinant of viable S. epidermidis adhesion to lenses. Strain variability, including levels of exopolysaccharide expression, and the solution used for lens immersion also influenced adhesion.
School of Optometry, University of California, Berkeley, USA.
S M
SM
Fleiszig
D J
DJ
Evans
M F
MF
Mowrey-McKee
R
R
Payor
T S
TS
Zaidi
V
V
Vallas
E
E
Muller
G B
GB
Pier
D001422:Bacterial Adhesion / Q000502:physiology*; D003263:Contact Lenses, Hydrophilic; D006801:Humans; D013212:Staphylococcus epidermidis / Q000302:isolation & purification / Q000502:physiology*