Antibiotic resistance and virulence characterization of Pseudomonas aeruginosa strains isolated from respiratory tract infections

Objectives: The aim of this study was to analyze the resistance, virulence and biofilm production of PA strains from respiratory tract infections. Methods: All strains were tested for antibiotic susceptibility according to current EUCAST guidelines. Several resistance and virulence genes were detected by PCR. Biofilm formation was detected by the crystal violet method. Results: 38 strains (47.5%) were categorized as XDR, and 12 (15%) as MDR. Seven (10%) MBL producers were identified. The VIM gene was detected in two strains. Genes connected with aminoglycoside resistance: aac(6΄)-I and ant(2΄΄)-I were detected in 10 strains each, aac(6′)-Ib in 18 strains (21%), and aph (3’)-IV in 7 strains (8%). The most prevalent virulence genes were exoT (95%), apr (93%), A, phzS (95%), and plcH (95%). All the tested strains were strong biofilm producers. Conclusions: The results demonstrate high frequency and heterogeneity of virulence gene profiles among PA isolates from respiratory tract infections. A high number of MDR and XDR strains poses a serious threat for patients and shows clearly that new antimicrobial agents are needed.