Effect of nanoparticles on the gene expression of virulence factors of Pseudomonas aeruginosa

Pseudomonas aeruginosa, an opportunistic pathogen, is a primary contributor to illness and death among burn patients and individuals with compromised immune systems. There is a growing need for the exploration and advancement of alternative therapeutic approaches that offer fresh avenues to combat P. aeruginosa infections. This demand is continuously increasing, with heightened attention directed towards this area of research. This study included One hundred and twenty clinical specimens collected from patients with different infections from four hospitals in Baghdad, which were cultured on Cetrimide agar, Blood agar, and MacConkey agar plates for isolation and identification of P. aeruginosa. According to morphological and biochemical tests, 55 Pseudomonas aeruginosa isolates (45.8%) were found in all samples. The prevalence of these isolates was 28 (50.9%) in female patients, compared to 27 (49.0%) in male patients, as shown in table (4-1); the highest rate of bacterial infection was within the age group 31 (20-30 year), followed by 12 (31-40 year), 10 (41-50 year), and 2 (61-70 year) respectively. In the present study, results of biofilm formation by the microtiter plate method showed that ten isolates from 55 isolates (18.2%) were strong biofilm producers. Also, it was found that 21(38.2%) isolates were moderate biofilm producers, and the other isolates (n=24; 43.6%) were weak to produce the biofilm Prior to the introduction of Zinc oxide nanoparticles, Pseudomonas aeruginosa exhibited a considerably greater (p<0.01) biofilm formation compared to the post-addition of Zinc oxide nanoparticles. The results of the antibiotic susceptibility test, conducted using the disc diffusion method, revealed variations in antibiotic resistance among all P. aeruginosa isolates included in this study. According to the findings of this study, the antibiotics Levofloxacin, Ceftazidime, Imipenem, Tobramycin, and Aztreonam had the highest resistance to antibiotics: 89%, 89%, 80%, 73%, and 71% respectively. The isolates of P. aeruginosa were the strong, moderate, and weak biofilm used in this study and detected by PCR technique using the rspL gene as the housekeeping gene of P. aeruginosa. All the tested P. aeruginosa clinically contained the rspL gene. The results showed that the last gene was found in 80% of isolates that produce strong biofilm, while the rhlI gene was found in all potent biofilm isolates. Ten isolates from 55 isolates were potent biofilm producers, and 8 contained both lasI genes (80%), while rhlI was found in all these isolates. The quantitative PCR reaction experiment involved six highly proficient biofilm producer isolates of Pseudomonas aeruginosa, each containing two biofilm genes. These isolates were deliberately selected with varying sub-MIC values to ZnO-np. In this study, the mRNA expression of biofilm genes was examined through a quantitative RT-PCR assay, comparing the samples treated with ZnO-np to those left untreated, using concentrations below the minimum inhibitory concentration (MIC) for each sample during bacterial growth. The results revealed a significant down-regulation in biofilm genes in the present of ZnO-np. The results showed a significant positive correlation between gene expression of RSPL, lasI, and rhlI genes and biofilm formation using Pearson correlation analysis which included all the tested isolates before and after the treatment with ZnO-np.