Antimicrobial dressings


Introduction 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.


Authors:Peter Vowden, Kathryn Vowden, Keryln Carville. Full author details can be found on page 6.


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 skin1


. 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 microbes2


.


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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 bacteria6


.


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 management7, 8


.


Antimicrobial dressings offer many benefits. They are: n


Relatively easy to use n Widely available


Frequently cost less than antibiotics n Available without prescription1, 8 Have less risk of resistance.


n n . 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 years3, 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 skin6


.


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.


Box 1 Antiseptic agents and their formulation (adapted from1


Antiseptic Silver


Iodine Formulation/notes


Silver sulfadiazine: cream, impregnated dressings Ionic silver: impregnated dressings Nanocrystalline silver


Povidone iodine: solution, cream, ointment, sprays, impregnated dressings


Cadexomer iodine: ointment, paste, powder, impregnated dressings


Chlorhexidine


Polyhexamethyl- biguanide (PHMB)


Honey Acetic acid


Potassium permanganate


Solution, powder, impregnated dressings. Chlorhexidine may be used as an alternative for patients allergic to iodine


Solution, impregnated dressings


Amorphous honey or impregnated dressings Solution


Solution, tablets for dissolution )


S.1


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