Effects of Pseudomonas aeruginosa elastase and Exotoxin A on subcutaneous tissue following dermal trauma.

Abstract

Pseudomonas aeruginosa is an opportunistic pathogen of the skin, especially following severe trauma such as burning. It produces a large array of virulence factors, including Exotoxin A and elastase that can kill susceptible cells and digest collagenous tissue. To observe and measure their effects, these purified virulence factors were applied directly to subcutaneous tissue using a transdermal chamber implanted in mice. Elastase disrupted collagen formation in tissue, induced haemorrhage, and increased exudation into the chamber which was quickly resolved by the host. Exotoxin A reduced the number of fibroblasts and leukocytes in tissue, decreased collagen formation, and reduced exudation and the concentration of monocytes in the chamber reservoir; these effects being observed four days post treatment. The ability of these two virulence factors to alter collagen formation and production, and influence local populations of leukocytes, provides further insight into the aetiology of bacteraemia following P.aeruginosa infection of skin.