Evasion of cellular ocular defenses by contact lens isolates of Serratia marcescens.
OBJECTIVE
Contact lens contamination by Serratia marcescens can lead to the development of microbial keratitis and contact lens-induced acute red eye, particularly during overnight contact lens wear. The aim of this study was to investigate the interaction of S. marcescens with polymorphonuclear leukocytes (PMNs), which occur in closed-eye tears.


METHODS
The respiratory burst of PMNs, when incubated with S. marcescens, was measured using chemiluminescence. Phagocytosis of planktonic and biofilm-grown bacteria by PMNs was also determined.


RESULTS
Some strains of S. marcescens did not induce a respiratory burst from PMNs and resisted phagocytosis regardless of opsonization. Phagocytic resistance and growth in the presence of PMNs was markedly increased when bacteria were grown as a biofilm on a contact lens.


CONCLUSIONS
The ability of S. marcescens to resist phagocytosis and grow to high levels in the presence of PMNs, particularly when grown as a biofilm on contact lenses, may be a mechanism by which this bacterium can survive the ocular host defense system, grow, and cause keratitis or other adverse responses.
Hume
Emma B H
EB
Cooperative Research Centre for Eye Research and Technology, University of South Wales, Sydney, Australia. e.hume@crcert.unsw.edu.au
Stapleton
Fiona
F
Willcox
Mark D P
MD
D001431:Bacteriological Techniques; D001433:Bacteriolysis; D018441:Biofilms / Q000254:growth & development; D003261:Contact Lenses / Q000382:microbiology*; D009504:Neutrophils / Q000502:physiology*; D010587:Phagocytosis / Q000502:physiology*; D016897:Respiratory Burst / Q000502:physiology*; D012706:Serratia marcescens / Q000254:growth & development* / Q000302:isolation & purification