Different strains of Pseudomonas aeruginosa isolated from ocular infections or inflammation display distinct corneal pathologies in an animal model

Purpose. The present investigation sought to define the responses of mouse eyes to challenge with three different strains of P. aeruginosa isolated from human corneas or contact lenses: two different strains produced an ulcerative keratitis, and one strain produced contact lens-induced acute red eye (CLARE). Methods. The corneas of BALB/c mice were inoculated with three different strains of P. aeruginosa. The strains were allowed to interact with the corneas for up to 24 h. In addition, strain Paerl, isolated from GLARE, was subjected to in vitro assays to measure its ability to invade corneal epithelial cells, or to produce cytotoxicity in these cells. Both these assays used cultured rabbit corneal epithelial cells. Results. Both MK isolates were able to infect the corneas of mice, but the GLARE isolate was non-infective. The predominant response to infection with the cytotoxic strain was severe corneal edema and infiltration of the corneal stroma with polymorphonuclear leukocytes (PMNs). The predominant response with the invasive MK isolate was corneal ulceration and infiltration with PMNs. The GLARE strain produced only low levels of PMN infiltration. In in vitro assays the GLARE strain was non-invasive and non-cytotoxic. Conclusions. This study has identified that P. aeruginosa produces at least three different types of corneal pathology and that not all strains are able to infect mouse corneas.