Antibacterial Properties of Ag-Cu Alloy Nanoparticles Against Multidrug-Resistant Pseudomonas aeruginosa Through Inhibition of Quorum Sensing Pathway and Virulence-Related Genes.

Objective

To evaluate the application of Ag-Cu NPs as quorum sensing (QS) inhibitors and attenuate virulence expression to overcome the global crisis of multidrug-resistant (MDR) P. aeruginosa.

Methods

Ag-Cu NPs were synthesized by co-reduction of silver-nitrate and copper-nitrate (Ag:Cu = 1:1 0.75 μM). In this cross-sectional study, a total of eighty clinical strains of P. aeruginosa were collected from patients with burns. The antibacterial and resistance pattern of the clinical isolated was determined using the microdilution and Kirby Bauer disk methods. The effect of sub-MIC of Ag-Cu NPs on the expression of lasI, exoS and toxA in five clinical isolates of imipenem-resistant P. aeruginosa was performed using qRT-PCR.

Results

The characterization methods confirm the formation of the Ag-Cu alloy NPs with agglomerated spherical morphology and particle sizes of about 30-40 nm. We observed that the MIC and MBC of Ag-Cu alloy NPs against MDR P. aeruginosa was found to be 2.5 and 5 μg ml-1, respectively. The effects of a sub-inhibitory concentration of Ag-Cu NPs on MDR P. aeruginosa QS and virulence-related genes showed that the expression level of QS regulatory and virulence genes significantly decreased in both MDR P. aeruginosa and reference strain under Ag-Cu sub-MIC treatment.

Conclusion

Ag-Cu NPs could be potentially used as a promising QS inhibitor and anti-virulence compound against P. aeruginosa.