Nanomedicine among several approaches is considered of potential therapeutic value. So, zinc oxide nanoparticles (ZnO-NPs) conjugated with clinically approved drugs (β-lactam Antibiotic) was synthesized with the aim to investigate the effect of ZnO NPs and ZnO NPs-antibiotics combinations against clinically isolated Pseudomonas aeruginosa that showed significant resistance to β-lactam antibiotic carbenicillin and detecting the level of ampC gene expression before and after ZnO NPs exposure. A total of, 10 isolates of P. aeruginosa were identified. The minimum inhibitory and bactericidal concentrations (MIC and MBC, respectively) of ZnO NPs and carbenicillin were determined using the colony counting method. Quantitative real-time PCR (RT-qPCR) was performed to estimate the expression of ampC. ZnO NPs with nanoscale size were effectively synthesized using the sono-chemical co-precipitation method as a simple and cost valuable method. ZnO NPs were highly effective against clinically isolated P. aeruginosa in a dose-dependent pattern. Moreover, the combination of ZnO NPs with carbenicillin increased the antibacterial activity of carbenicillin. Finally, the expression of ampC was down regulated due to ZnO NPs treatment and the down regulation was inversely proportional. Combination of ZnO NPs and carbenicillin highly induced down regulation of ampC gene without significant differences among different concentrations used.



