Bacterial invasion of corneal epithelial cells.
OBJECTIVE
The normal ocular surface is frequently colonized by commensal gram-positive species. Gram-negative bacteria are often implicated in corneal infection and inflammation, particularly in association with soft contact lens wear. The aim of this study was to elucidate possible mechanisms of virulence in ocular bacteria.


METHODS
The susceptibility of a human corneal epithelial cell line to bacterial invasion and association was evaluated using the gentamicin exclusion assay. Organisms tested included isolates from corneal ulcers, corneal inflammation and ocular sites in asymptomatic individuals.


RESULTS
The commensal, non-pathogenic bacterium Staphylococcus epidermidis and some pathogenic strains of Serratia marcescens did not invade corneal epithelial cells. In contrast, pathogenic strains of Pseudomonas aeruginosa associated with and invaded corneal epithelial cells.


CONCLUSIONS
The increased association of P. aeruginosa, compared to other bacterial types, might be a reason for the more frequent association of this bacterium with contact-lens-associated microbial keratitis.
Vallas
V
V
Cornea and Contact Lens Research Unit, and Cooperative Research Centre for Eye Research and Technology, University of New South Wales, Sydney, Australia.
Stapleton
F
F
Willcox
M D
MD
D001419:Bacteria / Q000472:pathogenicity*; D018407:Bacterial Physiological Phenomena; D002478:Cells, Cultured; D003315:Cornea / Q000166:cytology / Q000382:microbiology*; D004847:Epithelial Cells / Q000382:microbiology; D006801:Humans; D011550:Pseudomonas aeruginosa / Q000502:physiology; D012706:Serratia marcescens / Q000502:physiology; D013045:Species Specificity; D013212:Staphylococcus epidermidis / Q000502:physiology