Role of Pseudomonas aeruginosa extracellular enzymes in lung disease.

A variety of approaches have been employed in an attempt to assess the role of P. aeruginosa extracellular factors in lung infections due to this organism. Isogenic mutants, deficient in single virulence determinants, have been compared to parental strains in a variety of experimental animal models. Purified virulence factors have been instilled into the lungs of experimental animals in order to demonstrate comparable histopathological changes to those which occur during human infections. Serum antibody levels to various extracellular virulence factors have been measured in different patient populations, and inactivated virulence determinants have been tested for their ability to act as protective immunogens in animal model infections. The results from these studies suggest that P. aeruginosa extracellular factors including exotoxin A, proteases, hemolysins and exoenzyme S may play a significant role in the pathogenesis of P. aeruginosa lung infections.