Detection of the pqsA Gene and Histological Changes Induced by Pseudomonas aeruginosa

Pseudomonas aeruginosa uses quorum-sensing systems to coordinate activities regulated by specific genes, such as metabolic and environmental responses. The pqsA gene is a key component of the pqs pathway (quinolone signaling in Pseudomonas aeruginosa).This study focused on applying a mouse model to some local isolates of P. aeruginosa and identifying those carrying the pqsA gene. The study included isolating 150 samples for analysis, which resulted in confirmation of the presence of 58 isolates of P.aeruginosa. The specimens including wound swabs, burn samples, urine samples, middle ear swabs, and sputum were collected from different hospitals. The presence of the pqsA gene was confirmed molecularly using polymerase chain reaction (PCR) on 19 selected isolates, all of which showed positive amplification (448 bp). The experimental mouse model consisted of Swiss albino mice, divided into a control group and two treatment groups with low (1×10⁴ CFU) and high (1×10⁸ CFU) concentration of bacteria. We evaluated body weight before and after exposure and also performed histological examinations of the liver and lung tissue. The results showed that increased bacterial concentrations led to increased weight loss and extensive histological changes. In contrast, low concentrations produced only minor tissue changes. Statistical analysis (results are presented as means ± SE calculated using one-way ANOVA) confirmed these findings as statistically significant (p ≤ 0.05). Based on the above information, it can be concluded that the pqsA gene is highly conserved in local isolates of P. aeruginosa and that the presence of this gene leads to significant effects in host tissue in controlled in vivo studies. Therefore, this research contributes to understanding of the bacterial quorum sensing mechanism, the pathogenicity of bacterial species and their ability to interact with host bacteria in in vivo studies