Protease phenotypes of Pseudomonas aeruginosa isolated from patients with cystic fibrosis

Abstract

The protease phenotypes expressed by isolates of P. aeruginosa from cystic fibrosis (CF) patients were evaluated. Most isolates produced elastase (65%) and/or alkaline protease (64%). The mucoid phenotype expressed by many CF isolates of P. aeruginosa did not absolutely restrict the expression of protease activity, although a higher percentage of nonmucoid isolates was proteolytic. When isolates from CF patients chronically infected with P. aeruginosa were compared to isolates from CF patients colonized with this organism, both groups were found to contain comparable percentages of elastase-producing strains and mucoid strains. The group of isolates from colonized patients contained a higher percentage of strains producing alkaline protease and expressing general protease activity. The group of isolates from chronically infected patients contained more weakly proteolytic isolates than either the group from colonized CF patients or a group of isolates from pediatric patients without CF. Protease production may thus be important in the initial colonization of the respiratory tract of CF patients by P. aeruginosa.