title: Phenotypic characterization of clonal and nonclonal Pseudomonas aeruginosa strains isolated from lungs of adults with cystic fibrosis.
abstract: The emergence of virulent Pseudomonas aeruginosa clones is a threat to cystic fibrosis (CF) patients globally. Characterization of clonal P. aeruginosa strains is critical for an understanding of its clinical impact and developing strategies to meet this problem. Two clonal strains (AES-1 and AES-2) are circulating within CF centers in eastern Australia. In this study, phenotypic characteristics of 43 (14 AES-1, 5 AES-2, and 24 nonclonal) P. aeruginosa isolates were compared to gain insight into the properties of clonal strains. All 43 isolates produced bands of the predicted size in PCRs for vfr, rhlI, rhlR, lasA, lasB, aprA, rhlAB, and exoS genes; 42 were positive for lasI and lasR, and none had exoU. Thirty-seven (86%) isolates were positive in total protease assays; on zymography, 24 (56%) produced elastase/staphylolysin and 22 (51%) produced alkaline protease. Clonal isolates were more likely than nonclonal isolates to be positive for total proteases (P = 0.02), to show elastase and alkaline protease activity by zymography (P = 0.04 and P = 0.01, respectively), and to show elastase activity by the elastin-Congo red assay (P = 0.04). There were no other associations with genotype. Overall, increasing patient age was associated with decreasing elastase activity (P = 0.03). Thirty-two (74%) isolates had at least one N-acylhomoserine lactone (AHL) by thin-layer chromatography. rhl-associated AHL detection was associated with the production and level of total protease and elastase activity (all P < 0.01). Thirty-three (77%) isolates were positive for ExoS by Western blot analysis, 35 (81%) produced rhamnolipids, and 34 (79%) showed chitinase activity. Findings suggest that protease activity during chronic infection may contribute to the transmissibility or virulence of these clonal strains.
authors: Department of Infectious Diseases and Immunology, Blackburn Building DO6, University of Sydney, 2006 NSW, Australia.
authors: Pholawat
authors: P
authors: Tingpej
authors: Lucas
authors: L
authors: Smith
authors: Barbara
authors: B
authors: Rose
authors: Hua
authors: H
authors: Zhu
authors: Tim
authors: T
authors: Conibear
authors: Khaled
authors: K
authors: Al Nassafi
authors: Jim
authors: J
authors: Manos
authors: Mark
authors: M
authors: Elkins
authors: Peter
authors: P
authors: Bye
authors: Mark
authors: M
authors: Willcox
authors: Scott
authors: S
authors: Bell
authors: Claire
authors: C
authors: Wainwright
authors: Colin
authors: C
authors: Harbour
mesh_terms: D000293:Adolescent; D000328:Adult; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D015373:Bacterial Typing Techniques; D003550:Cystic Fibrosis / Q000382:microbiology*; D005260:Female; D006801:Humans; D008168:Lung / Q000382:microbiology*; D008297:Male; D008875:Middle Aged; D010447:Peptide Hydrolases / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D011552:Pseudomonas Infections / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity
chemical_list: D001426:Bacterial Proteins; D010447:Peptide Hydrolases