Type III Secretion System (Exoenzymes) as a Virulence Determinant in Pseudomonas aeruginosa Isolated from Burn Patients in Mansoura University Hospitals, Egypt

 Pseudomonas aeruginosa (P. aeruginosa) is an important causative organism of burn infection. Several virulence factors are implicated in P. aeruginosa colonization and invasion, making P. aeruginosa infection's outcome worse. Type III secretion system (T3SS) effector proteins are among these virulence factors. The present study evaluated the frequency of genes encoding T3SS effectors as a virulence determinant in P. aeruginosa isolates from burn patients.

 Wound swabs were collected from burn patients admitted to the Plastic and Reconstructive Surgery Center, Mansoura University, Egypt, and identified by different microbiological testing methods. The modified Kirby Bauer's disc diffusion method was used to test the antibiotic susceptibility of P. aeruginosa isolates against different antibiotics. Prevalence and the presence of exo genes that encode type T3SS proteins (exoS, exoT, exoU, and exoY) in P. aeruginosa isolates were evaluated by the multiplex PCR. Chi-square and Fisher's test were used for statistical analysis.

A total of 45 P. aeruginosa isolates were identified from 101 burn patients, including 27 males and 18 females, with a mean age of 15.78±2.65 years old. P. aeruginosa isolates were mostly susceptible to piperacillin/tazobactam and imipenem (73.33 and 62.22%), respectively; while the lowest susceptibility rates were in ceftazidime (4.44%), Tobramycin (4.44%), and ceftriaxone (6.67%). The exoY and exoT genes were detected in 100% of the P. aeruginosa isolates, while 62.22% and 42.22% of cli nical isolates harbored exoS and exoU genes, respectively.

 This study established a correlation between T3SS proteins, particularly exoS and exoU genes and antimicrobial resistance in P. aeruginosa isolates from burn infection.