Antimicrobial efficacy of a novel silver hydrogel dressing compared to two common silver burn wound dressings: Acticoat™ and PolyMem Silver ®

A novel burn wound hydrogel dressing has been previously developed which is composed of 2-acrylamido-2-methylpropane sulfonic acid sodium salt with silver nanoparticles. This study compared the antimicrobial efficacy of this novel dressing to two commercially available silver dressings; Acticoat™ and PolyMem Silver®. Three different antimicrobial tests were used: disc diffusion, broth culture, and the Live/Dead® Baclight™ bacterial viability assay. Burn wound pathogens (P. aeruginosa, MSSA, A. baumannii and C. albicans) and antibiotic resistant strains (MRSA and VRE) were tested. All three antimicrobial tests indicated that Acticoat™ was the most effective antimicrobial agent, with inhibition zone lengths of 13.9-18.4 mm. It reduced the microbial inocula below the limit of detection (10 2 CFU/ml) and reduced viability by 99% within 4 h. PolyMem Silver® had no zone of inhibition for most tested micro-organisms, and it also showed poor antimicrobial activity in the broth culture and Live/Dead® Baclight™ assays. Alarmingly, it appeared to promote the growth of VRE. The silver hydrogel reduced most of the tested microbial inocula below the detection limit and decreased bacterial viability by 94-99% after 24 h exposure. These results support the possibility of using this novel silver hydrogel as a burn wound dressing in the future

Inflammatory responses of a human keratinocyte cell line to 10 nm citrate- and PEG-coated silver nanoparticles

Silver nanoparticles (AgNPs) are among the most commonly used engineered NPs and various commercially available products are designed to come in direct contact with the skin (wound dressings, textiles, creams, among others). Currently, there is limited understanding of the influence of coatings on the toxicity of AgNPs and in particular their ability to impact on AgNP's mediated inflammatory responses. As AgNPs are often stabilized by different coatings, including citrate and polyethyleneglycol (PEG), in this study we investigate the influence of citrate (Cit10) or PEG (PEG10) coatings to 10 nm AgNP on skin, using human HaCaT keratinocytes. AgNPs cytotoxicity and inflammatory response (nuclear factor (NF)-kappa B induction and cytokine production) of HaCaT were assessed after in vitro exposure to 10 and 40 A mu g/mL after 4, 24, and 48 h. Results showed that although both types of coated AgNPs decreased cell proliferation and viability, Cit10 AgNPs were more toxic. NF-kappa B inhibition was observed for the highest concentration (40 A mu g/mL) of PEG10 AgNPs, and the putative link to early apoptotic pathways observed in these cells is discussed. No production of IL-1 beta, IL-6, IL-10, and TNF alpha was stimulated by AgNPs. Furthermore, Cit10 and PEG10 AgNPs decreased the release of MCP-1 by HaCaT cells after 48 h of exposure. As cytokines are vital for the immunologic regulation in the human body, and it is demonstrated that they may interfere with NPs, more research is needed to understand how different AgNPs affect the immune system