Effect of gold nanoparticles on the expression of efflux pump mexA and mexB genes of Pseudomonas aeruginosa strains by Quantitative real-time PCR

Antibiotic-resistant Pseudomonas aeruginosa infections are usually difficult to treat, and there are limited antibiotics for treating them. Increased antibiotic resistance of this bacterium, especially in a multidrug form, has caused many problems for treatment. Nowadays, metal nanoparticles are considered as appropriate alternatives to antibiotics. The objective of the present study was to investigate the effect of gold nanoparticles on the expression of MexB and MexA genes in Pseudomonas aeruginosa isolates.Pseudomonas aeruginosa isolate was identified using biochemical tests and an API kit. The antibiotic sensitivitytest for different antibiotics was performed withthe Kirby-Bauer test according to the CLSI standard. The presence of MexB and MexA genes was assessed by PCR. The effect of gold nanoparticles was investigated by microdilution to evaluate the minimum inhibitory concentration, and the expression of MexB and MexA treated genes was done with silver nanoparticles by the Real-Time PCR method.40 Pseudomonas aeruginosa isolates were detected and identified. These isolates showed significant resistance to various antibiotics. All strains were carriers of MexB and MexA genes, and finally, in the expression of MexB and MexA genes,a significant decrease in the expression of these genes was observed in the samples treated with gold nanoparticles compared to non-treated samples.One of the mechanisms of antibacterial activity of gold nanoparticles is through reducing the expression of mexA and mexB genes and thus reducing the number of active efflux pumps at the cell surface.