Pathogenesis of Pseudomonas aeruginosa Ocular Diseases

The gram-negative opportunistic bacterial pathogen, Pseudomonas aeruginosa, is an important etiologic agent of a variety of infectious diseases affecting the eye and surrounding tissues. The number of clinical studies and studies with mouse, guinea pig, and rabbit models of Pseudomonas-induced ocular disease has increased markedly in recent years, and this research has led to our improved understanding of factors relating to the pathogenesis and management of the diseases. Factors that predispose to ocular infections with P. aeruginosa include (1) trauma to the cornea with, or implantation of, foreign bodies or substances contaminated with the bacteria; (2) the presence of preexisting ocular disease; (3) immunosuppressive chemotherapy; and (4) presumed immunoincompetency in premature infants. The results of studies with animal models support the idea that the severe corneal damage that occurs during pseudomonas keratitis is caused by the production of bacterial enzymes and toxins that injure or kill the cellular components and/or degrade the extracellular matrix of the cornea and by bacterial product-mediated release or activation of cornea-degrading enzymes from corneal cells and/or from polymorphonuclear leukocytes infiltrating the infected cornea.