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: Biofilm formation is an important survival strategy and persistence mode between epidemic outbreaks of the facultative human pathogens V. cholerae and ETEC (Ahmed et al., 2013; Colwell et al., 2003). Recent findings suggest, that biofilms are a likely form in which V. cholerae and ETEC are taken up by humans, providing a concentrated infective dose (Ahmed et al., 2013; Colwell et al., 2003; Hall-Stoodley and Stoodley, 2005; Huo et al., 1996; Seper et al., 2011; Tamayo et al., 2010). Since biofilms are generally known to promote resistance against several antimicrobial agents (Lewis, 2005, 2008), we analyzed the impact of NPs on V. cholerae or ETEC biofilms. Therefore, we allowed V. cholerae or ETEC to form static biofilms for 24 h before ZnO-NPs-L, ZnO-NPs-F, Ag-NPs-L or Ag-NPs-F were added. Addition of LB broth, C. procera fruit or leaf extract served as controls, respectively. Finally, after an additional incubation period of 24 h the biofilm amount was quantified by crystal violet staining (Fig. 5). Addition of plant extract (fruit or leaf) had either no or a beneficial effect on biofilm formation in comparison to the LB control. Thus, the NPs treated biofilms were compared with the appropriate fruit or leaf plant extract, respectively. Addition of Ag-NPs-F showed no change in biofilm formation of both pathogens (Fig. 5A and B). In case of ETEC, treatment with ZnO-NPs-L, ZnO-NPs-F and Ag-NPs-L significantly reduced the biofilm amount compared to the plant extract treated control, respectively (Fig. 5B). This could also be observed for Ag-NPs-L treated biofilms of V. cholerae (Fig. 5A). In contrast, treatment with ZnO-NPs-L and ZnO-NPs-F had an opposite effect and significantly increased the biofilm amount of V. cholerae.
Affiliation: University of Graz, Institute of Molecular Biosciences, BioTechMed-Graz, Humboldtstrasse 50, A-8010 Graz, Austria; South Valley University, Faculty of Science, Qena, Egypt.