Antimicrobial Dressings: The Silver Mystique

As mentioned in our last posting, SSIs are the most common and costly of all hospital-acquired infections in the US.1 If you happened to have missed it, read it here. Accordingly, efforts to reduce SSI rates have led to the development of post-op dressings with antimicrobial agents impregnated within the dressing. These dressing inhibit the growth of, or kill a broad spectrum of microbes, at the surgical site.2

Dressings currently on the market incorporate three different antimicrobial agents:

  • Polyhexamethylene biguanide (PHMB) is an antimicrobial agent used in wound dressings, contact lens solutions, mouth wash and perioperative cleansing products; PHMB kills microorganisms by disrupting the cell membrane3
  • Silver’s (Ag) antimicrobial properties stem from its ability to be absorbed into the microorganism and bind DNA, resulting in cell death2
  • Chlorhexidine Gluconate (CHG) has been used worldwide as an antiseptic since 19544 and is effective against a broad spectrum of gram-positive and gram-negative bacteria, yeasts, and some viruses; chlorhexidine is the active antimicrobial agent, and chlorhexidine gluconate is a commonly used form of chlorhexidine because it is colorless, odorless, and easily dissolves in water.5

A closer look at silver
The use of silver in wound care was documented as early as 69 BC.6 Silver has broad spectrum antimicrobial activity against bacteria, yeast, fungi and mold. Topical silver-containing creams and ointments have been a mainstay of wound management in burn patients for years.7 Silver has been incorporated into various medical devices, including hemodialysis catheters, endotracheal tubes and urinary catheters.5

In order to have an antimicrobial effect, silver must be in the form of a charged particle (or ion).2 These silver ions are absorbed by bacteria, which in turn bind to the DNA structures to affect cell function and respiration. The overall effect is an interruption of bacterial replication and reduced formation of colonies.

There is a wide range of silver dressings and their methods of antimicrobial action is diverse.2 The variations stem from those that actively deliver silver to the wound surface either in low or high concentrations, and others that retain and kill bacteria within the structures of the dressing.

While the industry has widely debated the safety of silver in relation to systemic absorption and toxicity to human cells, it is thought that this occurs when silver ions are released into the wound bed too quickly over a sustained period of time.2 It is important to note, however—that in extensive recent reviews—the Centers for Disease Control and Prevention (CDC), the World Health Organization (WHO,) and the Cochrane Library) found no evidence that the use of dressings containing silver reduces rates of SSI.8-10

The aim of post-operative wound care is to allow the wound to quickly heal without complications, avoiding unnecessary discomfort for the patient, minimizing scarring, and preventing blood loss.11-12 The choice of post-op dressing is a critical component of wound management. Attributes of an ideal wound healing environment dictate the characteristics of an ideal post-op wound dressing.

Be sure to join us next time for a big announcement from Eloquest Healthcare.

References:

  1. Ban KA, Minei JP, Laronga C, et al. American College of Surgeons and Surgical Infection Society: surgical site infection guidelines, 2016 update. J Am Coll Surg. 2017;224(1):59-74.
  2. Hewish J. Understanding the role of antimicrobial dressings. Wounds Essentials 2012;1:84-90. http://www.wounds-uk.com/pdf/content_10457.pdf. Accessed February 13, 2017.
  3. Mulder GD, Cavorsi JP, Lee, DK. Wounds. Medscape website. 2007;19:173-82. http://www.medscape.com/viewarticle/561512_3. Accessed February 15, 2017.
  4. Krishna MT, Huissoon A. Peri-operative anaphylaxis: Beyond drugs and latex. Int Arch Allergy Immunol 2015;167:101-21.
  5. ChlorhexidineFacts.com website. http://www.chlorhexidinefacts.com/the-molecule.html. Accessed February 15, 2017.
  6. Murphy PS, Evans GRD. Advances in wound healing: a review of current wound healing products. Plastic Surg Int. 2012: doi:10.1155/2012/190436.
  7. Parsons D, Bowler PG, Myles V, Jones S. Silver antimicrobial dressings in wound management: a comparison of antibacterial, physical, and chemical characteristics. Medscape website. http://www.medscape.com/viewarticle/513362_3. Accessed February 15, 2017.
  8. Berríos-Torres SI, Umscheid CA, Bratzler DW, et al. Healthcare infection control practices advisory committee. Centers for Disease Control and Prevention guideline for the prevention of surgical site infection, 2017. eAppendix 2. JAMA Surg. Published online May 3, 2017. Doi:10.1001/ jamasurg.2017.0904.
  9. Allegranzi B, Zayed B, Bischoff P, et al. New WHO recommendations on intraoperative and postoperative measures for surgical site infection prevention: an evidence-based global perspective. Lancet. 2016;16:e288-303.
  10. Dumville JC, Gray TA, Walter CJ, et al. Dressings for the prevention of surgical site infection (review). Cochrane Database of Systematic Reviews 2016, Issue 12. Art. No.: CD003091. DOI: 10.1002/14651858.CD003091.pub4.
  11. Yao K, Bae L, Yew WP. Post-operative wound management. Australian Fam Physic. 2013;42:867-70.
  12. Incision Care. Encyclopedia of Surgery Website. http://www.surgeryencyclopedia. com/Fi-La/Incision-Care.html. Accessed February 14, 2017.