Part 3: How to use antimicrobial dressings on chronic wounds
The first two articles of this series looked at how to recognise wound infection and wound dressing types. For this article, we are going to explore why antimicrobial dressings should be used selectively rather than routinely, and how the choice should be based on a holistic assessment of the wound.
Chronic wounds, including pressure ulcers, venous leg ulcers, and diabetic foot ulcers, continue to be a frequent and complex health challenge in all healthcare settings. They affect a significant proportion of the population, particularly the elderly and those with underlying medical conditions such as diabetes, vascular disease, and compromised immune systems (Guest et al., 2015).
Chronic wounds are characterised by prolonged healing times, often exceeding six weeks, and are associated with significant pain, reduced quality of life, and increased healthcare costs (Posnett & Franks, 2008). The underlying pathophysiology of chronic wounds often involves impaired wound healing mechanisms, including disrupted inflammatory responses, reduced angiogenesis, and excessive matrix metalloproteinase (MMP) activity (Frykberg & Banks, 2015).
One of the key factors that affects wound healing is the presence of bacteria. While all chronic wounds are colonised with bacteria, the transition from colonisation to infection can significantly impede the healing process (Bowler et al., 2001). Wound infection can lead to increased inflammation, tissue damage, and the formation of biofilms, which are complex communities of bacteria encased in a self-produced matrix that are highly resistant to antimicrobial agents and host defences (Percival et al., 2011).
Antimicrobial dressings are an important tool in the management of chronic wounds at risk of or exhibiting signs of infection. These dressings contain antimicrobial agents, such as silver, iodine, polyhexanide (PHMB), and honey, which are designed to reduce the bioburden within the wound bed and promote healing. However, incorrect and prolonged use of antimicrobial dressings can contribute to the development of resistant bacteria, compromising their effectiveness and potentially limiting treatment options in the future (World Health Organisation, 2014).
When should we use Antimicrobial Dressings?
The decision to use an antimicrobial dressing should be based on a thorough assessment of the wound and the patient, considering the potential benefits and risks of treatment. It is important to undertake a holistic wound assessment using the TIME framework (Tissue, Infection/Inflammation, Moisture balance, Edge of wound) as this provides a structured approach, enabling nurses to identify subtle signs of infection or critical colonisation (Ousey et al. 2016).
Current guidelines and best practice recommendations emphasise the importance of using antimicrobial dressings selectively, rather than as a routine measure for all chronic wounds (EWMA, 2013; NICE, 2019).
There are several key indicators which suggest an antimicrobial dressing may be beneficial:
Clinical signs of infection:
Two or more signs of local wound infection, such as increasing pain, redness, swelling, warmth, purulent exudate, and malodour, in a previously stable wound bed, may indicate the need to use of an antimicrobial dressing (Cutting & White, 2004). These signs suggest that the bacterial burden is interfering with the wound healing process.
Critical colonisation:
Although some wounds may not show the classic signs of infection (especially in patients with diabetes or immunocompromised conditions), they may exhibit signs of critical colonisation, a state where the bacterial burden is high enough to affect wound healing but without the patient showing systemic symptoms. Signs of critical colonisation can be subtle and may include non-healing, increased exudate, friable granulation tissue, and a change in wound appearance (Sibbald et al., 2006).
High risk of infection:
In some situations where a wound is at high risk of infection, prophylactic use of antimicrobial dressings may be considered. This may include wounds in patients with compromised immune systems, wounds that are heavily contaminated (e.g., with faeces), and wounds that are difficult to manage with standard wound care practices (EWMA, 2013). The use of prophylactic antimicrobials should be discussed with the Tissue Viability Team to ensure that there is no other option available to improve wound healing.
Malodorous wounds:
Antimicrobial dressings can be used to manage malodour associated with certain types of wounds, even in the absence of overt infection. This is particularly relevant for patients with fungating tumours or infected wounds where odour significantly impacts their quality of life (Woo & Sibbald, 2009).
How to select the right Antimicrobial Dressings:
All dressings should be selected for the properties in managing the symptoms of the wound rather than just for their antimicrobial properties. For example, if the wound needs good exudate management, then you would choose a hydro fibre or alginate dressing which has antimicrobial properties. It may be worth revisiting the second article of this series to re-familiarise yourself with the generic properties of the dressing types so that you can choose appropriately.
The selection of the most appropriate antimicrobial dressing depends on several factors, including the type of wound, the level of exudate, the presence of infection, patient allergies, and cost-effectiveness. There is a wide range of antimicrobial dressings available, each with its own advantages and disadvantages. The availability of these dressings will also depend on what is available via your local wound dressing formulary.
Silver dressings:
Silver is a broad-spectrum antimicrobial agent that acts on the bacterial cell membranes and inhibits bacterial growth (White & Cutting, 2006). Silver dressings are available in various forms, including silver-impregnated foams, non-adhesives, hydro fibres and alginates. They are effective against a wide range of bacteria, including Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. However, concerns have been raised about the potential for silver resistance with prolonged use (Ip et al., 2010) and there is a possibility of silver staining in the wound bed that can resemble unhealthy or necrotic tissue.
Iodine-containing dressings:
Iodine is another broad-spectrum antimicrobial agent that works by oxidising microbial proteins and nucleic acids (Bigliardi et al., 2017). The preferred choice is Cadexomer iodine, which is a modified form of iodine that releases iodine slowly, minimising cytotoxicity, and promoting wound healing (Hansson, 2009). This is available as Iodoflex paste, Iodosorb ointment or Iodosorb powder. There are restrictions to the use of iodine such as pregnancy, patients taking Lithium tablets, or those suffering from thyroid gland problems, so please ensure you read the manufacturer’s instructions prior to using it.
Polyhexanide (PHMB) dressings:
PHMB is a synthetic antimicrobial agent that disrupts bacterial cell membranes. It is generally well-tolerated and has a broad spectrum of activity against bacteria, fungi, and viruses. PHMB dressings are available in various forms, including solutions, gels, and impregnated dressings (Kramer et al., 2005). PHMB is considered to be less cytotoxic than other antimicrobial agents.
Honey dressings:
Medical-grade honey, particularly Manuka honey, has antimicrobial properties due to its high sugar content, low pH, and the presence of methylglyoxal (MGO), which interacts to disrupt the bacterial DNA (Molan, 1999). Honey can also promote wound healing by stimulating new blood vessel growth and reducing inflammation (Gethin et al., 2008). Honey dressings are particularly useful for managing wounds with high odour and promoting autolytic debridement. Honey should be used with caution on diabetics and wounds with a poor blood supply or high pain levels.
What to consider when using an antimicrobial dressing:
Regardless of the choice of antimicrobial dressings, it is important to consider the following points so that their effectiveness is maximised alongside reducing the risks of complications.
Wound bed preparation:
The wound bed should be properly prepared before applying an antimicrobial dressing. This includes cleansing the wound with a suitable wound cleanser, debriding any necrotic tissue, and ensuring that the wound bed is adequately moist (Gray et al., 2011).
Dressing selection:
The dressing should be selected based on the type of wound, the level of exudate, and the presence of infection, as discussed previously.
Dressing application:
The dressing should be applied according to the manufacturer’s instructions. It is important to ensure the dressing is in direct contact with the wound bed and it is properly secured.
Dressing change frequency:
The frequency of dressing changes will depend on the type of dressing, the level of exudate, and the patient’s individual needs. Generally, dressings should be changed when they become saturated with exudate or when there are signs of infection (NICE, 2019).
Secondary dressings:
A secondary dressing may be required to absorb excess exudate and protect the wound. The choice of secondary dressing will depend on the level of exudate and the patient’s comfort.
Why is monitoring and evaluation so important?
It is the responsibility of all clinicians making prescribing decisions in wound care to optimise the use of antimicrobials and promote antimicrobial stewardship. Regular monitoring, evaluation, and clear documentation is essential to assess the effectiveness of antimicrobial dressings and to identify any potential complications.
It is important to monitor for any sign of allergy/adverse reaction, skin reaction or irritation, alongside changes to the symptoms of the wound itself. Antimicrobial dressings should only be used for 2 – 4 weeks and if, after this time, there is no significant improvement in the wound condition, a referral to a Tissue Viability Nurse is important.
By promoting regular wound assessment, clear rationale for choice of antimicrobial dressing, and only using them for the recommended length of time, healthcare professionals can optimise patients’ wound healing outcomes, reduce the risk of antimicrobial resistance, and manage chronic wounds with evidence-based knowledge and skills.
The previous articles in this series look at:
Wound Management Series Part 1: How to swab wounds correctly and recognise wound infection
Wound Management Series Part 2: Picking the correct wound dressing
Please cite as: OSKA Care Ltd. (May 2025). Wound Management Series Part 3: The correct use of antimicrobial dressings on chronic wounds. Havant, Portsmouth: OSKA Care Ltd.
References:
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