Abstract
Five strains of
Pseudomonas aeruginosa differing in their production of various virulence factors were examined for their ability to cause pyelonephritis when injected intravenously into mice. The severity of infection produced was found to correlate with the degree of production
in vitro of the protein exotoxin A, except in a strain which also simultaneously produced a protease. A strain which produced both haemolysin and exotoxin A caused a more persistent infection than one which produced more exotoxin A but no haemolysin.
These findings support the current view that exotoxin A is the most clearly identifiable virulence factor of
Ps. aeruginosa, but suggest that the final outcome of infection may depend on an interplay with other factors produced by individual strains.