Synthesis and antibacterial activity of ZnO nanoparticles on blaOXA and blaTEM gene expression in Pseudomonas aeruginosa

Abstract

Background: The rising percentage of multidrug resistant (MDR) Pseudomonas aeruginosa has emerged as a major clinical challenge in part because of the abundant transfer of β-lactamase-associated resistance genes, especially blaOXA and blaTEM. Recently, zinc oxide nanoparticles (ZnO-NPs) have been recognized as potential antimicrobial and resistance-modifying agents. Methods: In this study we assessed the effects of biosynthesized ZnO nanoparticles on blaOXA and blaTEM gene expression in clinical P. aeruginosa isolates by quantitative real-time PCR (qRT PCR).Methods: Twenty-nine clinical isolates of P. aeruginosa were obtained from different clinical specimens. The isolates carrying blaOXA and blaTEM genes were identified by molecular screening. For gene expression analysis, three typical isolates that harbored both genes were chosen. Biosynthesized ZnO nanoparticles were injected at a minimum inhibitory concentration (MIC) of 1.25 mg/ml for 18–24 h. Relative gene expression was quantified by qRT-PCR and 16S rRNA was used as reference gene for gene expression and analysed by 2^-ΔΔCt method. The results indicated that the blaOXA expression was greatly decreased in the treated isolates after treatment with ZnO nanoparticle (mean fold change ranged from 1.12 ± 0.37 in untreated isolates to 0.32 ± 0.03 in treated isolates, which is ∼71% downregulation). On the other hand, blaTEM downregulation from 1.01 ± 0.02 to 0.78 ± 0.10 represented approximately 23% downregulation. Not significant for a statistically non-significant reduction in (P > 0.05) but the expression level of treated isolates was always lower than the untreated controls. Results: Biosynthesized ZnO nanoparticles inhibited β-lactamase resistance genes in P. aeruginosa, in particular the genes for blaOXA. These results indicate that ZnO nanoparticles can be used as resistance modifying agents and may form an important target to control the future strategies for the prevention of antimicrobial resistance.