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.