The influence of exo-enzyme S and proteases on endogenous Pseudomonas aeruginosa bacteraemia in mice.

The role of Pseudomonas aeruginosa exo-enzymes was evaluated in a murine model of endogenous bacteraemia in which the bacteria invaded the bloodstream after oral dosing. Although an elastase mutant PAO-E64 was as virulent as its parent strain PAO1, an exo-enzyme S-deficient mutant, DG1-ExS5 and alkaline protease mutants PAKS-16, PAKS-17, PAKS-19, were less virulent than their parent strains, DG1 and PAKS-1, respectively (p < 0.01). Thus exo-enzyme S and alkaline protease, but not elastase, appear to contribute to the pathogenicity of P. aeruginosa in this model.