Cocktail Of Cuo, Zno, Or Cuzn Nanoparticles And Antibiotics For Combating Multidrug-Resistant Pseudomonas Aeruginosa Via Efflux Pump Inhibition

Multidrug resistant (MDR) bacteria have become an extremely serious public health concern. Bacteria can develop resistance through various mechanisms. Drug extrusion by the multidrug efflux pumps represents an important mechanism of antimicrobial resistance. Inhibitors of bacterial efflux pumps as adjuvants in antibacterial therapy are a reasonable and cost-effective pursuit since the shortage of antibiotics threatens global human health. Combined use of inorganic nanoparticles (NPs) with conventional antibiotics constitutes a promising alternative for fighting antibiotic resistance as NPs could restore the activity of the existing antibiotics. In the present study, the potential role of polyol-coated CuO, ZnO, and CuZn NPs as efflux pump inhibitors has been investigated against MDR clinical strains of Pseudomonas aeruginosa. The mode of action of the NPs was evaluated by studying their synergistic activity in combination with the antibiotics meropenem and ciprofloxacin, and their efflux inhibitory activity was studied by real-time fluorometry and a cartwheel assay. The results showed that the NPs act synergistically, in a concentration-dependent manner, with antibiotics known to be subject to efflux. Furthermore, the killing effect of the synergistic combinations over time was determined by time-kill studies. All the NPs at the lowest tested concentration enhanced the antibacterial activity of ciprofloxacin, as it was evidenced by both checkerboard and time-kill assays. Real-time fluorometric analyses revealed that NPs at sub-inhibitory concentrations promote the intracellular accumulation of ethidium bromide (EtBr). The EtBr agar cartwheel method showed that the NPs at the sub-minimum inhibitory concentration increased the fluorescence even at lower concentrations of EtBr, whereas in the absence of NPs, there was a much lower fluorescence. These results suggest that NPs may serve as potential sources of efflux pump inhibitors in order to tackle antimicrobial resistance.