Ceftazidime-Decorated Gold Nanoparticles: a Promising Strategy against Clinical Ceftazidime-Avibactam-Resistant Enterobacteriaceae with Different Resistance Mechanisms

Abstract

Nanoparticle-based antibiotic delivery systems are essential in combating antibiotic-resistant bacterial infections arising from acquired resistance and/or biofilm formation. Here, we report that the ceftazidime-decorated gold nanoparticles (CAZ_Au NPs) can effectively kill clinical ceftazidime-avibactam-resistant Enterobacteriaceae with various resistance mechanisms. Further study of underlying antibacterial mechanisms suggests that CAZ_Au NPs can damage the bacterial cell membrane and increase the level of intracellular reactive oxygen species. Moreover, CAZ_Au NPs show great potential in inhibiting biofilm formation and eradicating mature biofilms via crystal violet and scanning electron microscope assays. In addition, CAZ_Au NPs demonstrate excellent performance in improving the survival rate in the mouse model of abdominal infection. In addition, CAZ_Au NPs show no significant toxicity at bactericidal concentrations in the cell viability assay. Thus, this strategy provides a simple way to drastically improve the potency of ceftazidime as an antibiotic and its use in further biomedical applications.

Keywords: Enterobacteriaceae; antimicrobial resistance; ceftazidime-avibactam; gold nanoparticles.

FIG 1

Synthesis and characterizations of ceftazidime-decorated gold nanoparticles (CAZ_Au NPs). (A) Scheme for the synthesis of CAZ_Au NPs. (B) Size distribution intensity plot generated by dynamic light scattering (DLS) for CAZ_Au NPs. (C) Representative transmission electron microscopy (TEM) images of CAZ_Au NPs. (D) TEM mapping of CAZ_Au NPs. PDI, polydispersity index; d, diameter. HAADF, high-angle annular dark-field.

FIG 2

CAZ_Au NPs induce bacterial growth inhibition and lysis via the elevation of cell membrane permeability and reactive oxygen species (ROS). (A) Growth curve of ceftazidime-avibactam (CZA)-resistant Enterobacteriaceae after various treatments. (B) Representative TEM images indicating the morphologies of CZA-resistant Enterobacteriaceae after various treatments. (C) Representative CLSM images showing the cell membrane permeability of CZA-resistant Enterobacteriaceae after various treatments. (D) Fluorescence intensity analysis of intracellular ROS in CZA-resistant Enterobacteriaceae after various treatments by using a ROS assay kit. NS, normal saline; OD₆₀₀, optical density at 600 nm; PBS, phosphate-buffered saline; PI, propidium iodide.

FIG 3

CAZ_Au NPs inhibit the form of biofilm and eradicate mature biofilm ex vivo. (A) The biofilm-inhibitory effects of various treatments by measuring absorbance at 595 nm of crystal violet-stained CZA-resistant Enterobacteriaceae biofilms. (B) Biofilm-eradication effects of the various treatments by measuring absorbance at 595 nm (OD₅₉₅) of crystal violet-stained CZA-resistant Enterobacteriaceae biofilms. (C) Representative scanning electron microscope (SEM) images indicating the biofilm-inhibitory effects of CZA-resistant Enterobacteriaceae after various treatments. (D) Representative SEM images demonstrating the biofilm-eradication effects of CZA-resistant Enterobacteriaceae after various treatments.

FIG 4

CAZ_Au NPs improve the survival for mice with intraperitoneal infection caused by CZA-resistant Enterobacteriaceae. (A) Workflow of experimental processing. (B) Survival rate and body weight of CZA-resistant Enterobacteriaceae-infected mice after various treatments at different time points.

FIG 5

Cell viability of the Huh-7 and ACHN cells treated with different concentrations of CAZ_Au NPs tested by using the CCK-8 kit for 24 h. ns, not significant.