Lecture Points To Emerging Bacterial Resistance To Silver

At the recently concluded scientific sessions of the American Professional Wound Care Association (APWCA), Adrianne P.S. Smith, MD, presented evidence of evolving bacterial resistance to silver.

Silver dressings are, of course, frequently utilized in wound care. It has been generally accepted that natural resistance to silver does not occur. However, Dr. Smith noted that silver resistance is being increasingly reported. The origins of this resistance include: plasmids with encoded genes for silver resistance; bacterial chromosomes; and selection when too low a dosage of silver exposure allows bacterial survival.

Dr. Smith reported that Klebsiella sp., E. Coli, Pseudomonas stutzeri, and Acinetobacter baumannii were among bacterial species that have already demonstrated silver resistance. She noted that bacterial tolerance to silver could result from extended exposure to silver in addition to inadequate concentration or too slow a release of silver into the wound. Dr. Smith noted that debridement to remove biofilms and enhance wound healing increases the effectiveness of silver in general.

Dr. Smith further noted that copper alloy may be the next popular metallic bactericidal agent. She noted that the Environmental Protection Agency (EPA) has approved copper antibacterial agents and pointed out that copper alloy surfaces eliminate 99.9 percent of all bacteria, including MRSA, within two hours. In addition, she noted that copper resistance has already been reported.

Dr. Smith is President and Medical Consultant for the Wound Professional Services of San Antonio.



Anonymoussays: May 31, 2009 at 12:25 pm

This is unfortunate news. It would make sense that Copper would have similar resistance issues since it is chemically similar to Silver. It appears that these agents would be best suited for already healing wounds, rather than those wounds that are heavily infected. Recall that historically Silver was used to dress burns and only aid in the healing process. Are there any dressings available with multiple bacteria cidal strategies such as osmotic pull, pH change, temperature change, plus an "active" agent? Are current manufacturers manipulating the base material or simply relying on one active ingredient? Eons ago when I did compounding pharmacy, the base materials were always as important as the main ingredient. Both must work together for the maximum effect. Pharmacy has come a long way with respect to delivery systems & problem solving strategies. Are there any resources (grants) directed toward any pharmacy schools to help solve this crisis and develop better systems? Pharmacy schools have a lot of research tools available to generate outstanding viable products. Resistance is usually noted in the lab initially, and strategies to prevent it are already in progress before the products hit the market....and the patient.
Tammy J. Brown, DPM, RPh
tamdpm@yahoo.com

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