A novel, electrochemically synthesized, silver nanoparticles (AgNPs) formulation was evaluated in vitro against Pseudomonas aeruginosa, Burkholderia cepacia, Stenotrophomonas maltophilia, and Staphylococcus aureus strains from cystic fibrosis (CF) patients. AgNPs were particularly active against P. aeruginosa and B. cepacia planktonic cells (median MIC: 1.06 and 2.12 μg/ml, respectively) by a rapid, bactericidal and concentration-dependent effect. AgNPs showed to be particularly effective against P. aeruginosa and S. aureus biofilm causing a viability reduction ranging from 50% (1×MIC) to >99.9% (4×MIC). Electron microscopy showed that AgNPs deconstruct extracellular matrix of P. aeruginosa biofilm, and accumulate at the cell surface causing cell death secondary to membrane damage. Compared to Tobramycin, AgNPs showed comparable, or even better, activity against planktonic and biofilm P. aeruginosa cells. AgNPs at concentrations effective against B. cepacia and P. aeruginosa were not toxic to G. mellonella larvae. Our silver-based formulation might be an alternative to antibiotics in CF patients. Further in vitro and in vivo studies are warranted to confirm this therapeutic potential.

Helicobacter pylori colonizes approximately 50% of the world’s population, and it is the cause of chronic gastritis, peptic ulcer disease, and gastric cancer. The increase of antibiotic resistance is one of the biggest challenges of our century due to its constant increase. In order to identify an alternative or adjuvant strategy to the standard antibiotic therapy, the in vitro activity of newly synthesized Silver Ultra-NanoClusters (SUNCs), characterized by an average size inferior to 5 nm, against clinical strains of H. pylori, with different antibiotic susceptibilities, was evaluated in this study. MICs and MBCs were determined by the broth microdilution method, whereas the effect of drug combinations was determined by the checkerboard assay. The Minimum Biofilm Eradication Concentration (MBEC) was measured using AlamarBlue (AB) assay and colony-forming unit (CFU) counts. The cytotoxicity was evaluated by performing the MTT assay on the AGS cell line. The inhibitory activity was expressed in terms of bacteriostatic and bactericidal potential, with MIC₅₀, MIC₉₀, and MBC₅₀ of 0.33 mg/L against planktonic H. pylori strains. Using the fractional inhibitory concentration index (FICI), SUNCs showed potential synergism with metronidazole and clarithromycin. The biofilm eradication was obtained after treatment with 2×, 3×, and 4× MIC values. Moreover, SUNCs showed low toxicity on human cells and were effective in eradicating a mature biofilm produced by H. pylori. The data presented in this study demonstrate that SUNCs could represent a novel strategy for the treatment of H. pylori infections either alone or in combination with metronidazole.

This work highlights how our silver ultra nanoclusters (ARGIRIUM-SUNc) hand-made synthesized, are very useful as a bactericide and anti-biofilm agent. The Argirium-SUNc effective antibacterial concentrations are very low (< 1 ppm) as compared to the corresponding values reported in the literature. Different bacterial defense mechanisms are observed dependent on ARGIRIUM-SUNc concentrations. Biochemical investigations (volatilome) have been performed to understand the pathways involved in cell death. By using fluorescence techniques and cell viability measurements we show, for the first time, that membrane depolarization and calcium intracellular level are both primary events in bacteria death. The ARGIRIUM-SUNc determined eradication of different biofilm at a concentration as low as 0.6 ppm. This suggests that the effect of the nanoparticles follows a common mechanism in different bacteria. It is highly probable that the chemical constitution of the crosslinks could be a key target in the disrupting mechanism of our nanoparticles. Since the biofilms and their constituents are essential for bacterial survival in contact with humans, the silver nanoparticles represent a logical target for new antibacterial treatments.

The high prevalence of cardiovascular disease (CVD) is largely attributable to the contemporary lifestyle that is often sedentary and includes a diet high in saturated fats and sugars and low ingestion of polyunsaturated fatty acids (PUFAs), fruit, vegetables, and fiber. Experimental data from both animals and humans suggest an association between increased dietary fiber (DF) intakes and improved plasma lipid profiles, including reduced low density lipoprotein cholesterol (LDL-C) concentrations. These observations underline that the intake of DF may protect against heart disease and stroke.