Treatment of infection and inflammation associated with COVID-19, multi-drug resistant pneumonia and fungal sinusitis by nebulizing a nanosilver solution.

Solutions containing Ag0 nanoclusters, Ag+1, and higher oxidation state silver, generated from nanocrystalline silver dressings, were anti-inflammatory against porcine skin inflammation. The dressings have clinically-demonstrated broad-spectrum antimicrobial activity, suggesting application of nanosilver solutions in treating pulmonary infection. Nanosilver solutions were tested for antimicrobial efficacy; against HSV-1 and SARS-CoV-2; and nebulized in rats with acute pneumonia. Patients with pneumonia (ventilated), fungal sinusitis, burns plus COVID-19, and two non-hospitalized patients with COVID-19 received nebulized nanosilver solution. Nanosilver solutions demonstrated pH-dependent antimicrobial efficacy; reduced infection and inflammation without evidence of lung toxicity in the rat model; and inactivated HSV-1 and SARS-CoV-2. Pneumonia patients had rapidly reduced pulmonary symptoms, recovering pre-illness respiratory function. Fungal sinusitis-related inflammation decreased immediately with infection clearance within 21 days. Non-hospitalized patients with COVID-19 experienced rapid symptom remission. Nanosilver solutions, due to anti-inflammatory, antiviral, and antimicrobial activity, may be effective for treating respiratory inflammation and infections caused by viruses and/or microbes.

Improved Methods for Treatment of Phytopathogenic Biofilms: Metallic Compounds as Anti-Bacterial Coatings and Fungicide Tank-Mix Partners.

Fungi and bacteria cause disease issues in cultivated plants world-wide. In most cases, the fungi and bacteria colonize plant tissues as biofilms, which can be very challenging to destroy or eradicate. In this experiment, we employed a novel (biofilm) approach to crop disease management by evaluating the efficacies of six fungicides, and four silver-based compounds, versus biofilms formed by fungi and bacteria, respectively. The aim was to identify combinations of fungicides and metallic cations that showed potential to improve the control of white mold (WM), caused by the ascomycete fungus Sclerotinia sclerotiorum, and to evaluate novel high valency silver compounds as seed coatings to prevent biofilm formation of four bacterial blight pathogens on dry bean seeds. Our results confirmed that mature fungal biofilms were recalcitrant to inactivation by fungicides. When metallic cations were added to the fungicides, their efficacies were improved. Some improvements were statistically significant, with one combination (fluazinam + Cu2+) showing a synergistic effect. Additionally, coatings with silver compounds could reduce bacterial blight biofilms on dry bean seeds and oxysilver nitrate was the most potent inhibitor of bacterial blight.

Antiviral Activity of Ag5IO6, a Unique Silver Compound.

Pentasilver hexaoxoiodate (Ag5IO6) has broad-spectrum antimicrobial efficacy, including the long-term prevention of microbial adherence, the rapid killing of planktonic microorganisms, and the elimination of mature biofilms. This study's goal was to determine whether it may also have antiviral activity against structurally distinct viruses. Ag5IO6 was tested following ASTM E1052-20, Standard Practice to Assess the Activity of Microbicides Against Viruses in Suspension, against adenovirus type 5, murine norovirus, poliovirus type 1, SARS-CoV-2 (original), and SARS-CoV-2 (omicron) (host cells: H1HeLa, RAW 264.7, LLC-MK2, Vero E6, and Vero E6, respectively). A 0.1 g/mL Ag5IO6 suspension was prepared and the viruses were exposed for 30 min, 4 h, or 24 h. Exposure to Ag5IO6 resulted in complete kill of SARS-CoV-2 (omicron) within 30 min, as well as complete kill of both SARS-CoV-2 (original) and the murine norovirus within 4 h. Ag5IO6 showed increasing activity over time against the adenovirus, but did not achieve a 3-log reduction within 24 h, and showed no antiviral activity against the poliovirus. These results demonstrate that Ag5IO6 has antiviral activity against medically important viruses, in addition to its well-characterized antimicrobial activity, suggesting that it may be valuable in situations where the prevention or simultaneous treatment of microbes and viruses are necessary.

Bactericidal Efficacy of Oxidized Silver against Biofilms Formed by Curtobacterium flaccumfaciens pv. flaccumfaciens.

Bacterial wilt is a re-emerging disease on dry bean and can affect many other crop species within the Fabaceae. The causal agent, Curtobacterium flaccumfaciens pv. flaccumfaciens (CFF), is a small, Gram-positive, rodshaped bacterium that is seed-transmitted. Infections in the host become systemic, leading to wilting and economic loss. Clean seed programs and bactericidal seed treatments are two critical management tools. This study characterizes the efficacies of five bactericidal chemicals against CFF. It was hypothesized that this bacterium was capable of forming biofilms, and that the cells within biofilms would be more tolerant to bactericidal treatments. The minimum biocide eradication concentration assay protocol was used to grow CFF biofilms, expose the biofilms to bactericides, and enumerate survivors compared to a non-treated control (water). Streptomycin and oxysilver bisulfate had EC95 values at the lowest concentrations and are likely the best candidates for seed treatment products for controlling seed-borne bacterial wilt of bean. The results showed that CFF formed biofilms during at least two phases of the bacterial wilt disease cycle, and the biofilms were much more difficult to eradicate than their planktonic counterparts. Overall, biofilm formation by CFF is an important part of the bacterial wilt disease cycle in dry edible bean and antibiofilm bactericides such as streptomycin and oxysilver bisulfate may be best suited for use in disease management.

Does nanocrystalline silver have a transferable effect?

This study examined the mechanism of nanocrystalline silver antiinflammatory activity, and tested nanocrystalline silver for systemic antiinflammatory effects. Secondary ion mass spectroscopy of skin treated directly with nanocrystalline silver for 24 hours showed that at skin surfaces there were significant deposits at weights corresponding to Ag, AgO, AgCl, AgNO(3), Ag(2)O, and silver clusters Ag(2-6), but silver penetration was minimal. To test for translocation of the effect, a porcine contact dermatitis model in which wounds were induced on one side of the back and then treated with nanocrystalline silver on the opposite side of the back was used. Visual and histological data showed improvement relative to animals treated with saline only. Significantly increased induction of apoptosis in the inflammatory cells present in the dermis was observed with remote nanocrystalline silver treatments. In addition, immunohistochemical analysis showed decreased levels of proinflammatory cytokines tumor necrosis factor-alpha and interleukin-8, and increased levels of antiinflammatory cytokine interleukin-4, epidermal growth factor, keratinocyte growth factor, and keratinocyte growth factor-2. Thus, the antiinflammatory effects of nanocrystalline silver appear to be induced by interactions with cells in the top layers of the skin, which then release biological signals resulting in widespread antiinflammatory activity.

Evaluating antimicrobial efficacy of new commercially available silver dressings.

Prevention and treatment of bacterial colonised/infected wounds are critical. Many commercially available silver dressings claim broad-spectrum bactericidal activity over days and are indicated for serious conditions including burns and ulcers. However, there is no peer-reviewed literature available for many newer dressings. This study compared the activity of some of these dressings. Six silver-containing dressings were compared using log reduction, silver release and corrected zone of inhibition assays. Only the nanocrystalline silver dressing was bactericidal against Staphylococcus aureus, and the only other dressing that produced any log reduction was a silver collagen matrix dressing. These two dressings and a silver alginate dressing produced zones of inhibition, although the collagen matrix and alginate dressings had decreasing zone sizes over time, and the latter liquefied after five transfers. The remaining dressings (two ionic silver foam dressings and a silver sulphate dressing) did not produce zones of inhibition. For the foam, alginate and collagen matrix dressings, antimicrobial activity was related to silver release. The silver sulphate dressing released large quantities of silver, but only through the dressing edges, as the wound-contacting surface appeared to be hydrophobic. The results of this study emphasise the importance of confirming product claims regarding silver dressing efficacy.

Anti-inflammatory activity of nanocrystalline silver in a porcine contact dermatitis model.

The anti-inflammatory activity of nanocrystalline silver was examined using a porcine model of contact dermatitis. Inflammation was induced with dinitrochlorobenzene and then treated daily with nanocrystalline silver dressings, 0.5% silver nitrate, or saline. Erythema, edema, and histological data showed that nanocrystalline silver-treated pigs had near-normal skin after 72 hours, while other treatment groups remained inflamed. The decreased inflammation in the nanocrystalline silver-treated group was associated with increased inflammatory cell apoptosis, a decreased expression of proinflammatory cytokines, and decreased gelatinase activity. Silver nitrate treatments induced apoptosis in all cell types, including keratinocytes, resulting in delayed wound healing. These results demonstrate that nanocrystalline silver had a direct anti-inflammatory effect in the porcine contact dermatitis model that improved the overall outcome of the healing process. These data offer support that a species of silver (e.g., Ag(0)) that is uniquely associated with nanocrystalline silver may be responsible for the anti-inflammatory activity and improvement in healing.

Review: Antimicrobial efficacy validation using in vitro and in vivo testing methods.

Pre-clinical antimicrobial validation testing for single and combination products, and parameters that should be considered when testing the antimicrobial performance of a medical device, are discussed. Guidance is provided on key elements required for in vitro and in vivo antimicrobial validation, including validation of microbial growth, microbial recovery, neutralization, and antimicrobial activity. An important consideration, both in terms of practicality and economics, is designing in vitro studies that bridge to in vivo testing: A representative in vitro model is used to generate data on many clinically relevant microorganisms, and then one microorganism is selected for use in in vivo testing. If the in vivo results correlate to the in vitro results, it can reasonably be extrapolated that the same would be true for the remaining microorganisms tested in vitro. Thus, the selection of relevant in vitro models for testing is critical for successful antimicrobial validation testing.

Microbial Biofilms and Chronic Wounds.

Background is provided on biofilms, including their formation, tolerance mechanisms, structure, and morphology within the context of chronic wounds. The features of biofilms in chronic wounds are discussed in detail, as is the impact of biofilm on wound chronicity. Difficulties associated with the use of standard susceptibility tests (minimum inhibitory concentrations or MICs) to determine appropriate treatment regimens for, or develop new treatments for use in, chronic wounds are discussed, with alternate test methods specific to biofilms being recommended. Animal models appropriate for evaluating biofilm treatments are also described. Current and potential future therapies for treatment of biofilm-containing chronic wounds, including probiotic therapy, virulence attenuation, biofilm phenotype expression attenuation, immune response suppression, and aggressive debridement combined with antimicrobial dressings, are described.

Ag5IO6: novel antibiofilm activity of a silver compound with application to medical devices.

This work explores the unique antibiofilm activity of pentasilver hexaoxoiodate (Ag(5)IO(6)). To test this activity, wound dressings were impregnated with Ag(5)IO(6) and compared with various commercially available silver-containing dressings, as well as dressings containing chlorhexidine, iodine and polyhexamethylene biguanide (PHMB). The materials were tested against Pseudomonas aeruginosa, Staphylococcus aureus and Candida albicans for their ability to prevent micro-organism adherence, eliminate planktonic micro-organisms and disrupt/eliminate mature biofilms generated using the MBEC™ assay within 24 h of microbial exposure. Only the Ag(5)IO(6)-containing dressings were able to prevent adherence and eliminate surrounding planktonic micro-organisms for all species tested for ≥28 days of elution with log reductions >4. Two other silver dressings succeeded against P. aeruginosa only after 28 elution days, whilst the PHMB dressing succeeded after 28 days of elution against C. albicans only. Ag(5)IO(6)-containing dressings were able to generate >4 log reductions against all biofilms tested. The only commercial dressings able to generate >4 log reductions against biofilms were iodine against P. aeruginosa and S. aureus, and PHMB against S. aureus. The Ag(5)IO(6) dressings demonstrated complete kill (>4 log reduction) in a standard 30-min planktonic log reduction assay against all species. These results demonstrate that Ag(5)IO(6) has superior activity to a number of antimicrobials, with broad-spectrum efficacy that includes long-term prevention of microbial adherence, rapid kill of planktonic micro-organisms, and the ability to disrupt and eliminate mature biofilms. Thus, Ag(5)IO(6) may be a valuable antimicrobial agent for use in a number of medical device applications, including wound dressings, various catheters or implants.

Anti-inflammatory activity of nanocrystalline silver-derived solutions in porcine contact dermatitis.

BACKGROUND: Nanocrystalline silver dressings have anti-inflammatory activity, unlike solutions containing Ag+ only, which may be due to dissolution of multiple silver species. These dressings can only be used to treat surfaces. Thus, silver-containing solutions with nanocrystalline silver properties could be valuable for treating hard-to-dress surfaces and inflammatory conditions of the lungs and bowels. This study tested nanocrystalline silver-derived solutions for anti-inflammatory activity. METHODS: Inflammation was induced on porcine backs using dinitrochlorobenzene. Negative and positive controls were treated with distilled water. Experimental groups were treated with solutions generated by dissolving nanocrystalline silver in distilled water adjusted to starting pHs of 4 (using CO2), 5.6 (as is), 7, and 9 (using Ca(OH)2). Solution samples were analyzed for total silver. Daily imaging, biopsying, erythema and oedema scoring, and treatments were performed for three days. Biopsies were processed for histology, immunohistochemistry (for IL-4, IL-8, IL-10, TNF-alpha, EGF, KGF, KGF-2, and apoptotic cells), and zymography (MMP-2 and -9). One-way ANOVAs with Tukey-Kramer post tests were used for statistical analyses. RESULTS: Animals treated with pH 7 and 9 solutions showed clear visual improvements. pH 9 solutions resulted in the most significant reductions in erythema and oedema scores. pH 4 and 7 solutions also reduced oedema scores. Histologically, all treatment groups demonstrated enhanced re-epithelialisation, with decreased inflammation. At 24 h, pMMP-2 expression was significantly lowered with pH 5.6 and 9 treatments, as was aMMP-2 expression with pH 9 treatments. In general, treatment with silver-containing solutions resulted in decreased TNF-alpha and IL-8 expression, with increased IL-4, EGF, KGF, and KGF-2 expression. At 24 h, apoptotic cells were detected mostly in the dermis with pH 4 and 9 treatments, nowhere with pH 5.6, and in both the epidermis and dermis with pH 7. Solution anti-inflammatory activity did not correlate with total silver content, as pH 4 solutions contained significantly more silver than all others. CONCLUSIONS: Nanocrystalline silver-derived solutions appear to have anti-inflammatory/pro-healing activity, particularly with a starting pH of 9. Solutions generated differently may have varying concentrations of different silver species, only some of which are anti-inflammatory. Nanocrystalline silver-derived solutions show promise for a variety of anti-inflammatory treatment applications.

The kinetics of thermal instability in nanocrystalline silver and the effect of heat treatment on the antibacterial activity of nanocrystalline silver dressings.

The kinetics of nanocrystalline silver dressing heat treatment was investigated via isothermal heat treatments at 90 degrees C, 100 degrees C, and 110 degrees C lasting 2-50h. Bactericidal efficacy of the dressings was measured via log reductions, while bacteriostatic longevity was determined via plate-to-plate transfer corrected zones of inhibition. Morphological evolution of the dressing was studied by X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy, while changes in heat flow were measured by differential scanning calorimetry. Increasing temperature increased the rate at which dressing bactericidal activity and bacteriostatic longevity decreased. Once changes in dressing properties began, they occurred nonlinearly with time. The earliest biological, chemical, and physical indicators of altered dressing properties were loss of bacteriostatic longevity, silver-oxygen bonds, and fine features, respectively. An early change in heat flow appeared to be responsible for these indicators, while a later change corresponded to rapid grain growth occurring after a critical crystallite size (approximately 30 nm) was reached. The grain growth exponent was determined to be 2.8 for temperatures of 100-110 degrees C, with an activation energy of 177 kJ/mol, suggesting that normal grain growth occurred, with volume and/or grain boundary diffusion as the dominant forms of diffusion. The thermal instability of nanocrystalline silver should be accounted for during production, storage, and use of dressings. The properties required for nanosilver antimicrobial efficacy demonstrated in this study, as well as its thermal instability, should be taken into consideration for the development of nanosilver products in the future.