Molecular detection of exoS and exoU genes of Pseudomonas aeruginosa and its relation with antibiotic resistance.

Abstract

Pseudomonas aeruginosa is one of the most clinically important bacteria. It can cause serious infections because it has many virulence factors, which are the main reasons for the emergence of antibiotic resistance. The most important one is the type III secretion system (T3SS), which includes exoS and exoU toxins which play a main role in bacterial invasion.  Aim. The aim of this study was to identify the exoS and exoU genes that encoded for exoS and exoU toxins found in P. aeruginosa isolates and express their relationship with antibiotic resistance. Methods. The study included forty strains of P.aeruginosa isolated from different clinical samples of burns,wounds, and sputum from patients in Baghdad hospitals. The isolates were identified by microbiological methods and the VITEK-2 system. ExoS gene, which have size (230 bp) and exoU gene which have a size (1572 bp) were determined in forty P. aeruginosa by conventional PCR technique. Results. the result showed prevalence of exoS gene were (70.5%), (100%), and (90%) in isolates from burns, wounds, and sputum, respectively. Meanwhile, the presence of the exoU gene was determined in (29.4%), (30.7%), and (10%) from burns, wounds, and sputum, respectively. The antibacterial susceptibility test for each isolate was performed toward (14) antibiotics; the result revealed the resistance were (100%) to Amoxicillin, Piperacillin, and Cefixime; (97.5%) Cefazolin; (97%) Amoxicillin-Clavulanic acid; (92.5%)Tigeocyclin;(72.5%) Imipenem;(67.5%) Levofloxacin; (65%) Ceftazidime; (62%) Pepracillin\Tazobactam; (60%) Ciprofloxacin; (57.5%) Cefepime; (52.5%) Gentamicin and (40%) Amikacin. Conclusion. this study investigated that clinical isolates with high antibiotic resistance contained genes for toxin production (exoS and exoU), which means the greatest potential virulence factors of P.aeruginosa increase with the presence of exoS and exoU genes.