Molecular Detection of the exoU and toxA genes among Pseudomonas aeruginosa of patients with burn and wound infection in Baghdad City

Abstract

Background: Pseudomonas aeruginosa, a human opportunistic Gram-negative pathogen, is one of the most important nosocomial pathogens and is a major health problem, primarily in immunocompromised individuals. Aims: to isolate Pseudomonas aeruginosa of clinical samples (Burns, wounds) swab, in order to diagnose P. aeruginosa using culture media and VITEK2 device. To study of the resistance of P. aeruginosa towards some antibiotics with VITEK2. To detect exoU and toxA genes in Pseudomonas aeruginosa isolates with PCR techniques. Materials and Methods: The current study included a collection of (210) swabs from patients suffering burns and wound infections in both genders, (93) males and (117) females, with ages ranged from 5-78 years were included, for the period from November 2019 to the end of February 2020, samples were collected from Burns departments at different hospitals within Baghdad\ Iraq. Results: After final diagnosis of samples, 50(23.80%) isolates of P. aeruginosa were obtained from 16 (32%) burn swabs, and 34 (68%) of wound swab. The highest resistance of P. aeruginosa to antibiotics was against antibiotics Levofloxacin, Ceftazidime, Imipenem, Tobramycin and Aztreonam; 88%, 88%, 78%, 70%, 68% respectively by using Modified Kirby-Bauer method. The highest MIC of the antibiotics was 90% for Ticarcillin 64μg/mL, 96% for Ticarcillin/clavulanic acid 64μg/ mL, 96% for Piperacillin 64μg/ mL, and 96% for Piperacillin/Tazobactam 64μg/ mL. The bacterial DNA was extracted from 50 isolates of P. aeruginosa. The PCR was carried out for all bacterial isolates, using specialized primers, to detect these two genes (toxA and exoU). The results showed that the 20 P. aeruginosa isolates have the toxA gene in a percentage 40% from all isolates. The results also showed that the same 20 P. aeruginosa isolates have the gene exoU in a percentage 40% from all isolates. The presence of exoU and toxA virulence genes in wounds is high positive rate of burn infection, where they were 60% for burns and 40% for wounds. Conclusion: current study found that the bacterial isolates carrying the exoU gene were also containing the toxA gene, so their pathogenic potential would be higher than if they carried one of the two genes.