Correlation between the expression of the lasR quorum‑sensing gene, biofilm‑related genes, and exotoxin A in Pseudomonas aeruginosa isolates: a Rep-PCR-based fingerprinting analysis.

BACKGROUND

This study investigates the relationship between quorum sensing genes (lasR), biofilm-related genes (algD and pslD), and the virulence gene (toxA) in Pseudomonas aeruginosa, a major opportunistic pathogen known for its increasing antibiotic resistance.

METHODS AND

RESULTS

Our study was conducted on 100 P. aeruginosa strains isolated from 4 selected hospitals in Tehran, Iran. The antimicrobial test was determined using the disk diffusion method. Biofilm formation was tested on all isolates using the phenotypic method. The presence of lasR, algD, pslD and toxA genes was detected using PCR and confirmed through sequencing. The expression levels of the genes were measured using the real-time PCR. Isolates were typed by Rep-PCR at an 80% similarity level. Antimicrobial susceptibility testing revealed that 34% of isolates were classified as multidrug-resistant (MDR). Biofilm formation was observed in 78% of isolates. PCR analysis showed a high prevalence of lasR (80%), algD (88%), and toxA (83%), while pslD was detected in 42% of isolates. The co-occurrence of all genes was noted in 23 isolates, 22 of which were biofilm producers. Real-time PCR confirmed elevated expression of these genes in biofilm-producing isolates. Finally, Rep-PCR fingerprinting analysis revealed preliminary clonal relatedness patterns among 22 selected isolates, which were categorized into 4 common types (CT) and 14 single types (ST).

CONCLUSION

These findings highlight the relationship between Las quorum‑sensing system (specifically lasR), biofilm formation, and exotoxin A production in P. aeruginosa, underscoring the need for targeted strategies to combat MDR mediated bacterial infections.