What You Should Know About Using Silver Products In Wound Care
Whether it is used as a topical ingredient or a dressing ingredient, the use of silver in treating wounds has been around for quite some time. Silver has an array of beneficial effects in promoting healing. Given the potential of silver in the wound care arena, our expert panelists take a closer look at the history of silver in wound care, key indications and their experience with the different modalities that contain silver. Q: Historically, how has topical silver been used in wound care? A: The panelists note that silver has been recognized for centuries as a useful antimicrobial agent. In the early 19th century, surgeons used silver sutures to close incisions in surgeries (such as the repair of vesico-vaginal fistulas) that were known to commonly result in postoperative infections, according to Liza G. Ovington, PhD, CWS. She adds that diluted (1 to 2%) silver nitrate solutions were used commonly to treat gonorrhea. William Ennis, DO, MBA, Jason Weber, DPM, and Dr. Ovington also note that silver nitrate was used to prevent and/or treat eye infections in newborn babies. Drs. Ovington and Weber point out that thin sheets of silver foil were employed to cover open wounds as well as surgical wounds. While the advent of antibiotics such as penicillin in the 1930s led to a decline in the use of silver products as antimicrobials, all of the panelists note that silver, specifically silver sulfadiazine, has been commonly used as an antiseptic to help treat burn wounds since the 1960s. In addition, physicians use silver-coated catheters for their slow-release antiseptic activities, according to Dr. Ovington. There has also been a recent resurgence in employing topical silver in wound care. Dr. Ovington and Alan Cantor, DPM, CWS, say the advent of new sustained release delivery systems have made it possible for silver to be incorporated into a wide variety of dressing materials. Q: How do silver impregnated products promote wound healing and decrease infection? A: Dr. Ennis says silver has broad spectrum antimicrobial properties against a wide spectrum of gram-positive and gram-negative bacteria. By controlling the bioburden, silver facilitates less competition for nutrients and less production of toxic metabolites, according to Dr. Ennis. Dr. Cantor notes ionic silver, which is a key ingredient in modern wound dressings, promotes healing by facilitating the following: • decrease of matrix metalloproteinase (MMP) activity; • blocking of the respiratory cycle of bacterial cell wall membrane; • decrease of excessive neutrophil response; • regulation of inflammatory response without shutting off essential pro-healing functions; and • increase of surface levels of calcium. In other words, Dr. Ovington explains that silver impregnated products, which provide a sustained release of positively charged silver ions at the wound surface, can promote wound healing and decrease infection by killing bacteria. She adds that a decrease in bacterial numbers at the wound surface can result in fewer bacteria invading the deeper tissue compartment as well as decreased amounts of bacterially derived chemicals such as proteases and toxins that interfere with wound healing from a biochemical standpoint. Dr. Weber says silver ions exhibit their antimicrobial effect by “avidly binding” to negatively charged components in proteins and nucleic acids, thereby affecting structural changes in bacterial cell walls, membranes and other products that are believed to affect the viability of the organism. Specifically, he notes researchers believe silver ions interact with thiol groups, phosphates, indoles, imidazoles, carboxylates, amines and hydroxyls. In particular, the silver cation Ag+ is a “very potent antimicrobial agent because it can attack and damage bacterial cells at multiple sites,” notes Dr. Ovington.