In vitro activity of a new synthesized silver ultra-nanoclusters (SUNc) against Helicobacter pylori

The infectious diseases are still one of the most important current challenges. The success of the antibiotic therapy is limited by the significant increase of the antibiotic resistance. Helicobacter pylori infection is difficult to manage and the use of new therapeutic approaches is needed. It has been widely demonstrated that silver nanoparticles have a strong activity against Gram-positive and Gram-negative bacteria, as well as viruses and fungi. The aim of this study was to evaluate the antimicrobial activity of a new synthesized (EP-18181873) silver ultra-nanoclusters (SUNc) formulation against Helicobacter pylori. SUNc was tested versus eight clinical Helicobacter pylori isolates with a different antibiotic susceptibility pattern and one reference strain (ATCC 43504), using the broth microdilution methodology. Furthermore, the time killing assay was performed on the Helicobacter pylori ATCC 43504, at 24 and 48 hours of incubation. The inhibitory concentrations of SUNc were similar to the bactericidal ones, with values ranging from 0.16 to 0.33 μg/ml, independently from their susceptibility pattern. The 90% of the investigated strains was inhibited in its growth at 0.33 μg/ml and a decrease of CFU counts, corresponding to ~ 7 log10, was observed at MIC concentration in the treated samples after 24 h of incubation. The citotoxicity test on AGS cells, evaluated by using MTT assay, demonstrated that SUNc is not toxic until concentrations between 1.30-2.62 µg/ml. The data obtained showed that SUNc is active against Helicobacter pylori and could represent a novel strategy for the treatment of the infection especially in cases of multidrug resistance.