Antibacterial activity of silver and zinc nanoparticles against Vibrio cholerae and enterotoxic Escherichia coli.
Bottom Line: In order to investigate new effective and inexpensive therapeutic approaches, we analyzed nanoparticles synthesized by a green approach using corresponding salt (silver or zinc nitrate) with aqueous extract of Caltropis procera fruit or leaves.Using the expression levels of the outer membrane porin OmpT as an indicator for cAMP levels, our results suggest that zinc nanoparticles inhibit adenylyl cyclase activity.Finally, we demonstrated that a single oral administration of silver nanoparticles to infant mice colonized with V. cholerae or ETEC significantly reduces the colonization rates of the pathogens by 75- or 100-fold, respectively.
Affiliation: University of Graz, Institute of Molecular Biosciences, BioTechMed-Graz, Humboldtstrasse 50, A-8010 Graz, Austria; South Valley University, Faculty of Science, Qena, Egypt.Show MeSH
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Mentions: Based on these results ZnO-NPs may interfere in cAMP signaling and cause adverse effects. In addition, Ag-NPs-F had no impact on biofilm formation of both pathogens. Thus, Ag-NPs-L were selected for further analysis. First, the killing dynamic of Ag-NPs-L against log-phase cultures of V. cholerae and ETEC was determined (Fig. 7). Two different concentrations of Ag-NPs-L were tested, with one close to the MIC and the other 2-fold higher. Addition of Ag-NPs-L at these two different concentrations to a V. cholerae culture resulted in both cases in a rapid, continuous drop of viable cells with no detectable CFUs after 2 h (Fig. 7A). In the case of ETEC, killing was delayed with a steady decrease of CFUs over time for both concentrations tested. Finally no detection of viable cells could be observed after 20 h for the higher or 22 h for the lower concentration of Ag-NPs-L, respectively (Fig. 7B). Based on these results, Ag-NPs-L kill V. cholerae faster than ETEC. Furthermore, concentrations above the MIC do not shorten the duration of killing.
Affiliation: University of Graz, Institute of Molecular Biosciences, BioTechMed-Graz, Humboldtstrasse 50, A-8010 Graz, Austria; South Valley University, Faculty of Science, Qena, Egypt.