Background: In the last decades, nosocomial infections caused by drug-resistant Pseudomonas aeruginosa became a common problem in healthcare facilities. Antibiotics are becoming less effective as new resistant strains appear. Therefore, the development of novel enhanced activity antibacterial agents becomes very significant. A combination of nanomaterials with different physical and chemical properties enables us to generate novel multi-functional derivatives. In this study, graphene oxide and polyvinylpyrrolidone-stabilized silver nanoparticles hybrid nanocomposite (GO-Ag HN) were synthesized. The relation between antibiotic resistance and GO-Ag HN potential toxicity to clinical P. aeruginosa strains, their antibiotic resistance, and molecular mechanisms were assessed.
Methods: Chemical state, particle size distribution, and morphology of synthesized GO-Ag NH were investigated using spectroscopy and microscopy techniques (UV-Vis, FTIR, XPS, TEM, SEM, AFM). Broad-spectrum antibiotic resistance of P. aeruginosa strains was determined using E-test. Antibiotic resistance genes were identified using polymerase chain reaction (PCR).
Results: In this study, the toxicity of the GO-Ag NH to the isolated clinical P. aeruginosa strains has been investigated. A high antibiotic resistance level (92%) was found among P. aeruginosa strains. The most prevalent antibiotic resistance gene among tested strains was the AMPC beta-lactamase gene (65.6%). UV-vis, FTIR, and XPS studies confirmed the formation of the silver nanoparticles on the GO nanosheets. The functionalization process occurred through the interaction between Ag nanoparticles, GO, and polyvinylpyrrolidone used for nanoparticle stabilization. SEM analysis revealed that GO nanosheets undergo partial fragmentation during hybrid nanocomposite preparation, which remarkably increases the number of sharp edges and their mediated cutting effect. TEM analysis showed that GO-Ag HN spherical Ag nanoparticles mainly 9-12 nm in size were irregularly precipitated on the GO nanosheet surface. A higher density of Ag NPs was observed in the sheets' wrinkles, corrugations, and sharp edges. This hybrid nanocomposite poses enhanced antibacterial activity against carbapenem-resistant P. aeruginosa strains through a possible synergy between toxicity mechanisms of GO nanosheets and Ag nanoparticles. With incubation time increasing up to 10 minutes, the survival of P. aeruginosa decreased significantly.
Conclusion: A graphene oxide and silver nanoparticles hybrid composite has been shown to be a promising material to control nosocomial infections caused by bacteria strains resistant to most antibiotics.
Keywords: Pseudomonas aeruginosa; antibacterial activity; carbapenem-resistant bacteria; graphene oxide nanosheets; hybrid nanocomposite; silver nanoparticles.
© 2020 Lozovskis et al.