Molecular detection and expression of virulence factor encoding genes of Pseudomonas aeruginosa isolated from clinical samples

Introduction and Aim: Pseudomonas aeruginosa virulence factors genes are a growing concern as they are involved not only in its pathogenicity, but also cause bacterial resistance to multiple classes of antibiotics. Laboratory identification of clinical isolates carrying the virulence genes would be critical in limiting the bacteria's spread and reducing its pathogenicity. The purpose of this study was to investigate a simple and inexpensive real-time PCR test to find the level of expression of Pseudomonas aeruginosa virulence genes before and after treatment with specific concentration of Lactobacillus acidophilus cell-free supernatants (CFSs). Materials and Methods: Between December 2021 and June 2022, 350 clinical samples collected from Baghdad hospitals, Iraq, were tested for the presence of P. aeruginosa. The P. aeruginosa isolated were tested for their antimicrobial susceptibility using the Kirby-Bauer disk diffusion method. P. aeruginosa virulence genes were detected by using the reverse transcription-PCR method. The expression levels of these genes before and after treatment with Lactobacillus acidophilus cell-free supernatants were measured by real-time PCR. Results: Out of 350 samples tested, 60 isolates were positive for the presence of P. aeruginosa. Antibiotic susceptibility tests revealed a high level of antibiotic resistance, while genetic techniques identified the presence of several virulence genes that exhibited variable expression under the influence of Lactobacillus acidophilus supernatants. Conclusion: The study findings showed that L. acidophilus supernatants had an effect on reducing the expression of certain virulence genes of P. aeruginosa, implying that L. acidophilus could be used as an option in treating P. aeruginosa infection.