Abstract
Background: Biofilm formation is crucial in the pathogenesis of Pseudomonas aeruginosa infections, contributing to increased antibiotic resistance. Objectives: This study aimed to evaluate the expression of the PA0756 and toxA genes in clinical isolates of P. aeruginosa, comparing biofilm-producing isolates with planktonic ones. Methods: In this cross-sectional study, 160 clinical isolates of P. aeruginosa were collected from hospitals in Tabriz. Biofilm development was assessed using a 96-well flat-bottom microtiter plate test, followed by polymerase chain reaction (PCR) amplification of the resistance genes PA0756 and toxA. DNA synthesis for both biofilm and planktonic P. aeruginosa was conducted, with the quantification of target genes carried out using real-time PCR with specific primers. Results: Of the isolates, 139 (87%) formed biofilms. These strains showed high resistance to gatifloxacin, piperacillin, gentamycin, and ceftazidime (82.25%, 72.97%, 76.12%, and 74.63%, respectively), while resistance to colistin and polymyxin B was low (2.5% and 3%, respectively). The expression study revealed significant upregulation of the PA0756 and toxA genes in biofilm formers by 1.2 - 5.6 fold and 1.2 - 2.5 fold, respectively, compared to planktonic cells (P = 0.012 and P = 0.041, respectively). Conclusions: The PA0756 and toxA genes are significantly involved in biofilm-specific antibiotic resistance in P. aeruginosa, presenting potential targets for therapeutic interventions against antibiotic resistance caused by this pathogen.