Antimicrobial dressings made easy
01/02/11 | Acute Wounds, Complex wounds, Infection | Vowden P, Vowden K, Carville K.
Antimicrobial dressings play an important part in wound care in the prevention and management of infection. However, clinicians must be aware of their different properties and when to start and stop treatment in order to deliver cost- and clinically effective care.
What are antimicrobials?
Antimicrobials are agents that kill micro-organisms. Antimicrobial is an 'umbrella' term that includes: disinfectants, antiseptics and antibiotics. Disinfectants refer to chemical agents or biocides that are used to inhibit or kill microbes on inanimate objects such as dressing trolleys and instruments, for example, alcohol, sodium hyperchlorite and glutaraldehyde. Antiseptics, on the other hand, are biocides used to inhibit or kill micro-organisms present within a wound (the bioburden) or on intact skin . The antimicrobial activity of disinfectants and antiseptics varies considerably and these agents are referred to as bactericidal, fungicidal, virucidal or sporicidal when they kill microbes, and bacteriostatic, fungistatic, sporistatic or virustatic if they inhibit the growth of microbes . Some of the more traditional biocides such as sodium hyperchlorite and iodine have been used as disinfectants and antiseptics for over a century and their cytotoxic effect in wounds has been recognised for many years [3, 4, 5].
Many disinfectants and antiseptics have broad-spectrum antimicrobial activity and microbial resistance is uncommon. Antibiotics are naturally occurring or synthetically produced chemical substances that can act selectively and can be administered both topically (normally not recommended in wound care) or systemically. Microbial resistance to antibiotics is common and an increasing international concern.
What are antimicrobial dressings?
For the purpose of this document, antimicrobial dressings refer to wound dressings which have an antiseptic agent incorporated and does not include products/dressings which incorporate antibiotics. As described above, traditionally the term antiseptic has been used to refer to solutions that damage healthy tissue. Such solutions have a broad action and can be highly effective in killing micro-organisms but may compromise healthy tissue. Thus, their use in ongoing wound management has been questioned and limited to reducing the load of pathogens on intact skin .
Recent advances in antiseptic technology have led to the development of a number of products that are less harmful to healthy tissue, while being highly effective in destroying pathogens. These include antiseptics such as silver, cadexomer iodine, polyhexamethyl biguanide (PHMB) and honey. Dressings incorporating these antiseptics can successfully be used in topical management to reduce the load of a variety of pathogens, not just bacteria .
Partly due to the rising prevalence of drug-resistant antibiotics (thought to be in part a result of their indiscriminate and over-use), these antimicrobial dressings incorporating antiseptic agents are increasingly being used in wound management [7, 8].
Antimicrobial dressings offer many benefits.
- Relatively easy to use
- Widely available
- Frequently cost less than antibiotics
- Available without prescription [1, 8]
- Have less risk of resistance.
How do antiseptics work?
The commonly encountered antiseptic agents are listed in Box 1. Antimicrobial dressings are applied topically to the wound where they exert a broad spectrum of non-selective antibacterial action. They act at multiple sites within microbial cells, thus reducing the likelihood of bacteria developing resistance. This helps to explain their relatively low levels of bacterial resistance. This is unlike antibiotics which act selectively against bacteria and can be administered topically (not usually recommended) or systemically.
It is vital to ensure that the benefits of using antimicrobial dressings outweigh the potential negative effects on wound healing.
Other products which control bioburden by physical methods, eg by binding bacteria in exudate within the dressing, or by debridement, are not discussed within this document.