Prevalence of exoU/exoS genotype amongPseudomonas aeruginosa isolated from burn wound infections

Abstract

Pseudomonas aeruginosa has been identified as the main causative agent responsible for severe infections in burn patients worldwide. This study aimed to investigate the prevalence of the exoU/exoS genotype in P. aeruginosa isolates collected from burn wound infections in Iraq. From January to April 2023, a total of eighty isolates of P. aeruginosawere obtained from patients with burn wound infections in two Iraqi hospitals (Teaching Baghdad Hospital and AL-Yarmok Hospital).The isolates were first identified using biochemical tests and then verified using molecular techniques, specifically by targeting the 16S rRNA gene with specific primers. The exoU/exoS genotype was detected using conventional polymerase chain reaction (PCR) by specifically targeting two genes, exoS and exoU.The study found that burn wound infections contained four distinct genotypesof P. aeruginosa, and these genotypes exhibited substantial differences (P<0.001). The exoU-/exoS+ genotype exhibited a significantly higher prevalence of 75% (60 out of 80 isolates), whereas the exoU-/exoS- genotype had a comparatively lower prevalence of 5% (4 out of 80 isolates). At the same time, a lower percentage of isolates, 6.25 % (5 out of 80 isolates), was found to contain the exoU gene only (exoU+/exoS- genotype). Notably, 11 isolates (13.75 %) exhibited the presence of both exoS and exoU (exoU+/exoS+ genotype; a highly virulence isolate).bioinformatics analysis indicates that other bacterial species, such as Klebsiella pneumoniae, Enterobacter cloacae, and Acinetobacter baumannii, can produce ExoU toxin. The findingsprovide valuable insights into the genetic diversity of P. aeruginosa in burn wound infections, with the presence of highly virulent strains harbouring two genes (exoSand exoU gene).