with ocular infections and 84% of all isolates. The ability to
invade and replicate within epithelial cells may protect invasive
strains from host immune responses and certain antimicrobials
while still stimulating release of inflammatory mediators
and inducing tissue damage.14 Invasive strains of P.
aeruginosa may also directly kill epithelial cells after prolonged
incubation in a bacterial density-dependent manner.30
Aminoglycosides, and other poorly cell-permeable antimicrobials,
may be suboptimal therapeutics against invasive strains
of P. aeruginosa.31–33 A murine model of P. aeruginosa keratitis
has confirmed tobramycin, a non cell-permeable antibiotic,
is less effective at eradicating bacteria from corneas infected
with invasive strains than ofloxacin, a cell-permeable
antibiotic.34 Furthermore, that study demonstrated several aminoglycosides
and fluoroquinolones were capable of killing cytotoxic
and invasive strains when not cell-associated, but only
cell-permeable fluoroquinolones killed invasive strains within
corneal epithelial cells.