Synergistic antimicrobial potential of ciprofloxacin with silver nanoparticles conjugated to thiosemicarbazide against ciprofloxacin resistant Pseudomonas aeruginosa by attenuation of MexA-B efflux pump genes

Abstract

Pseudomonas aeruginosa is an important nosocomial pathogen. Metal nanoparticles (NPs) have shown a promising antibacterial activity against multidrug resistant strains. The purpose of this study was to investigate the synergistic antibacterial effect of silver nanoparticles functionalized by Thiosemicarbazid with ciprofloxacin and their effect on the expression of mexA-B efflux pump genes in ciprofloxacin resistant P. aeruginosa. Ciprofloxacin resistant P. aeruginosa strains were isolated from clinical specimens. Silver nanoparticles (Ag NPs) were functionalized using glutamic acid and conjugated with Thiosemicarbazid (TSC). Antibacterial synergism of Ag–TSC NPs with ciprofloxacin against P. aeruginosa and possible effect of the NPs on the expression of MexA and MexB genes were evaluated using quantitative PCR. The Ag-TSC NPs (concentration ≥ 32 μg/mL) displayed synergistic effects with ciprofloxacin (at sub-MIC concentration), which efficiently inhibited bacterial growth. Expression of mexA and mexB genes was reduced among the strains that simultaneously were exposed to the Ag –TSC NPs and ciprofloxacin by 6.0 and 2.75 folds, respectively, compared to the controls. In this study synergism of Ag-TSC NPs with ciprofloxacin against multi-drug P. aeruginosa by attenuation of ciprofloxacin resistance genes was observed, which could be promising to be used in antibacterial approaches.