Silver Nitrate: Antimicrobial Activity Related to Cytotoxicity in Cultured Human Fibroblasts

Abstract

The aims of this study were to ascertain whether silver nitrate (AgNO₃) concentrations below those used in clinical practice inhibit bacterial growth, and in parallel study the cytotoxic effects on human fibroblasts. The cytoprotective effects of fetal calf serum (FCS) were also evaluated. The cytotoxic effects of eight different silver nitrate concentrations were determined by assessing mitochondrial activity of viable cells capable of cleaving tetrazolium salts. Antimicrobial activity of AgNO₃, range: 7–550 × 10^–5%, was tested against Staphylococcus aureus, Citrobacter freundii, and Pseudomonas aeruginosa. Silver nitrate concentrations exerting antimicrobial effects were: S. aureus, >70 × 10^–5%; P. aeruginosa, ≥270 × 10^–5%, and C. freundii, ≥550 × 10^–5%. With 2% FCS, the lowest AgNO₃ concentration studied (7 × 10^–5%) showed cytotoxic effects (cell survival 71 ± 19%) at only 2 h of incubation. Under these conditions AgNO₃ cytotoxicity was time- and concentration-dependent in all exposure periods. Cytotoxicity was greatly enhanced causing 76% fibroblast growth inhibition at concenctrations of 14 × 10^–5% and contact time of 2 h. The AgNO₃ concentration of 7 × 10^–5% was also cytotoxic with 5% FCS in the media compared with controls, although cell survival was higher than with 2% FCS. The cytoprotective action of FCS was clearly shown at the concentration of 10% at which AgNO₃ cytotoxicity of 7 × 10^–5% to 28 × 10^–5% was partially or completely inhibited. Our results show that AgNO₃ at concentrations 100–700 times more diluted than that normally used in clinical practice retained effective inhibitory activity against some of the above-mentioned microorganisms. However, even these concentrations are cytotoxic for cultured fibroblasts. Thus, silver nitrate concentrations up to 100 times more diluted can be used, since they possess bacterial growth-inhibiting power, are less cytotoxic and therefore favour wound healing.

Cis-2-decenoic Acid Inhibits S. aureus Growth and Biofilm In Vitro: A Pilot Study

“…We used three wells for all combinations of C2DA with antibiotics, and four wells for biocompatibility tests. In studies of antimicrobial effects on toxicity, 50% to 100% reductions in viability were observed [5,11,24]. Given the approximate SD of 500 cells per well, we could detect a difference of 1500 cells per well (around 20% of control values) with 80% power using ANOVA analysis.…”

Skin Tissue Engineering for the Infected Wound Site: Biodegradable PLA Nanofibers and a Novel Approach for Silver Ion Release Evaluated in a 3D Coculture System of Keratinocytes and Staphylococcus aureus

“…To address this, some recent studies have tried to implement two-dimensional, monolayer coculture systems of cells and bacteria to test antimicrobial agents that can be added to the culture medium. [27][28][29][30] To date, there is no published method on evaluating antimicrobial dressings in coculture systems. Therefore, we designed a novel 3D coculture system to assess the cytotoxicity and antimicrobial properties of antimicrobial scaffolds/wound dressings in one experiment.…”

Nanocomposite and Nanostructured Carbon-based Films as Growth Substrates for Bone Cells

“…For example, in our study (Bacakova et al, 2008b) an LB medium, containing bacto-tryptone (10 g/l), bacto-yeast extract (5g/l) and NaCl (10g/l) in H 2 O was used. It has been reported that the serum supplement of the culture media has protective effects against the cytotoxic action of silver (Hidalgo et al, 1998;Sun et al, 2006). Thus, the promising results obtained in both studies by Bacakova et al (2008b) and Vasilev et al (2010) should be further investigated, particularly using the culture media of the same chemical composition for both mammalian and bacterial cells.…”