Molecular detection and identification of virulence factors of Pseudomonas aeruginosa isolated from wound and burn infections

In recent decades, Pseudomonas aeruginosa has emerged as one of the most important nosocomial pathogens. Due to the clinical importance this bacterium, various methods have been developed to rapidly and accurately identify it. The aim of this research was to detect P. aeruginosa isolated from wound and burn infections on the basis of the amplification of the oprI, oprL and toxA genes, and to determine the prevalence of nan1 and exoS genes among them. A total of 150 P. aeruginosa isolates was collected from patients with burn and wound infections of Imam-khomaini, Tohid and Motahari hospitals in Tehran. The isolates were identified as P. aeruginosa using specific biochemical tests. Chromosomal DNA of the isolates was extracted with phenol chloroform method and used for PCR of oprI, oprL, toxA, exoS and nanI genes by specific primers. Among 150 P. aeruginosa isolates all carried the oprl and oprL genes; 98 (65.3%), 142 (94.7%) and 19 (12.66%) of the isolates were positive for exoS, toxA and nanI genes respectively. The presence of nan1 gene in wound isolates (30%) was significantly higher (p<0.05) than in burn isolates (4%). ‍ Our results indicated that simultaneous use of oprl, oprL and toxA genes provide sufficient sensitivity to detect P. aeruginosa in clinical samples. The high prevalence of exoS in isolates suggests invasive phenotype of wound and burn isolates. The high prevalence of nan1 in wound isolates suggests a possible role of this gene in those infections.