Effect of adhered bacteria on the binding of Acanthamoeba to hydrogel lenses
A. I. Gorlin, M. M. Gabriel, L. A. Wilson and D. G. Ahearn
Department of Biology, Georgia State University, Atlanta, USA.
OBJECTIVES: To determine the effect of Pseudomonas aeruginosa and
Staphylococcus epidermidis on the binding of Acanthamoeba species to
hydrogel lenses. METHODS: Cells of amebae and bacteria were incubated with
different types of hydrogel lenses. Densities of amebae that were bound to
the lenses after rinsing were determined from direct counts with a cell
detachment procedure and from scintillation counts of cells, which were
radiolabeled with tritiated leucine. RESULTS: With both methods, amebae
showed significantly increased binding to hydrogel lenses with attached P
aeruginosa. The numbers of amebae that were retained on lenses with
attached S epidermidis were not significantly different from those that
were retained on lenses without bacteria. The binding of amebae to unworn
hydrogel lenses, in contrast to the irreversible adherence of P aeruginosa,
was tenuous. CONCLUSIONS: The binding of Acanthamoeba species to unworn
hydrogel lenses was tenuous and appeared to be related to water content,
surface tensions, and ionic charge. The presence of adhered P aeruginosa on
the hydrogel lenses facilitated the binding of Acanthamoeba species. The
cocontamination of lens systems with bacteria (eg, P aeruginosa) may be a
prime factor in the development of amebic keratitis.
