Genotypic and phenotypic characterization of Pseudomonas aeruginosa isolates from urinary tract infections

Pseudomonas aeruginosa is one of the most frequent agents of urinary tract infections especially in patients with indwelling urethral catheters. A total of 30 P. aeruginosa isolates from urinary tract infections was investigated for their genotypic and phenotypic characteristics. 'Single Nucleotide Polymorphism' chip typing experiments in combination with bioinformatical cluster analyses allowed genotypic grouping of the isolates. Some similarities to strains from lung infections but also to environmental strains were observed. Finally, several urinary tract-specific groups were identified indicating a strong heterogeneity of the urethral isolates. Pyoverdin, protease, and phospholipase A production in combination with quorum sensing activity and biofilm formation were common phenotypic characteristics of these strains. In contrast, swarming phenotypes, the production of pyocyanin, and the extracellular enzymes phospholipase C and elastase were rarely observed. Interestingly, strains isolated from catheter-associated infections showed significantly enhanced biofilm formation, decreased motility, and a slightly increased expression of virulence factors in relation to isolates from acute urinary tract infections.