We investigated a collection of Pseudomonas aeruginosa strains from hospitalized patients (n=20) and various environmental sources (n=214) for their genetic relatedness, virulence properties, antibiotic resistance and interaction with intestinal (Caco-2), renal (A-498) and lung (Calu-3) cell lines. Using RAPD-PCR, high diversity was found amongst the strains irrespective of their sources, with only six common (C) types containing strains from both a clinical and environmental source. Environmental strains belonging to these C-types showed higher adhesion to A-498 cells than clinical strains (17±13 bacteria/cell versus 13±11 bacteria/cell; p<0.001), whereas clinical strains adhered significantly greater to Calu-3 and Caco-2 cells than environmental strains (p<0.001 for both). The virulence genes (VGs) and antibiotic resistance profiles of the strains were similar, however the prevalence of environmental strains carrying both exoS and exoU was significantly (p<0.0368) higher than clinical strains. Whilst all strains were resistant to ticarcillin and ticarcillin/clavulanic acid, resistance against aztreonam, gentamicin, amikacin, piperacillin and ceftazidime varied among environmental and clinical strains. These results suggest that environmental strains of P. aeruginosa carry similar virulence properties to clinical strains, including adhesion to various human cell lines with some strains showing a higher adhesion to specific cell lines which indicate they may have a better ability to cause infection in those sites under predisposing conditions of the host.
Canadian Journal of Microbiology / Vol. 62, No. 3, pp.233-240