Age-dependent changes in protease and elastase production in cultures of Pseudomonas aeruginosa.

The intracellular and extracellular protease and elastase contents of Pseudomonas aeruginosa were studied in relation to the age of the culture. The intracellular protease and elastase content of the organisms decreased as the culture grew older, whereas extracellular protease and elastase greatly increased 24 h after incubation commenced, suggesting that host tissue injury by P. aeruginosa infection may increase in proportion to the duration of tissue colonisation.