Virulence factors genes and drug resistance in Pseudomonas aeruginosa strains derived from different forms of community and healthcare associated infections

Background: The pathogenesis of Pseudomonas aeruginosa (PA) infection is multifactorial and depends mainly on two types of virulence determinants: virulence factors involved in acute infections and membrane bound factors, and virulence factors involved in chronic infections. The aim of this laboratory-based study was to analyse the resistance and virulence of PA strains isolated from different types of infections in hospitalised and non-hospitalised patients in Southern Poland. Material/Methods: Non-repetitive samples from urinary tract infections (UTI), bloodstream infections (BSI) and pneumonia (PNU) were collected. Isolates were screened for the presence of virulence factors by PCR method. Antimicrobial susceptibility testing was performed using disc diffusion method. Metallo-beta-lactamases (MBLs) were detected using an imipenem-EDTA double-disc synergy test. Results: There were 232 specimens collected: UTI-152, PNU-69, BSI-11. Fifty-one (22%) strains were classified as multidrug resistant (MDR), 23 (10%) as extensively-drug resistant (XDR). MDR/XDR strains were more frequently isolated from pneumonia (OR = 2.28). The prevalence values for the genes of effector proteins were 82.8% for exoS, 89% for exoY, and 24% for exoU. The simultaneous detection of four effector proteins was confirmed in 10.4% of the strains. pilB was more prevalent in isolates from the elderly (p=0.013). lasB occurred more frequently in PNU (p=0.048). Three of the genes were more prevalent in isolates from patients hospitalised in ICU (lasB (p=0.017), aprA (p=0.022), phzS (p=0.039)). Conclusions: Understanding the contribution of selected virulence genes to the outcome of an infection may be important for the therapeutic management of patients infected with PA. Simultaneous detection of virulence factors and antimicrobial resistance might be particularly useful because both are clinically important during an infection.