In chronic wound follow-up, the phrase “antimicrobial dressing” often enters the conversation early. Finding bacteria on the wound surface, or a culture result, does not make this decision on its own. The clinical team assesses wound aetiology, perfusion, exudate, the surrounding skin, the course of healing, and the covert or overt clinical signs of infection together. The International Wound Infection Institute (IWII) frames this approach through the wound infection continuum, biofilm-based care, and antimicrobial stewardship. The decision on an antimicrobial dressing is made together with the clinical assessment of infection, the product’s intended use, the institutional protocol, and a planned time for reassessment.
The IWII framework: contamination, colonisation, infection
IWII describes wound infection as a stepwise continuum. Contamination is the transient presence of microorganisms on the wound surface; clinical signs of inflammation are not expected. Colonisation is the persistent settlement of microorganisms on the wound surface without a marked host response; delayed healing alone is not evidence of colonisation. Local infection is an increase in microbial burden together with clinical signs such as peri-wound erythema, increased warmth, oedema, increasing pain, or purulent exudate. Spreading infection and systemic infection are further stages; they fall within the field of urgent management and systemic treatment.
These steps do not translate directly into an “antimicrobial dressing yes/no” box on an order form. They do, however, give purchasing and the wound team common terminology: a report of colonisation does not mean an indication for infection treatment. The sequence to ask before dressing selection — aetiology, perfusion, exudate, infection — is summarised in before choosing a wound product.
Colonisation and infection: the clinical distinction
In colonisation, microorganisms are present in the wound bed; peri-wound erythema, progressive enlargement of the wound, increasing pain, or systemic findings may be absent. Even where a culture result reports growth, the clinician assesses the clinical picture as a whole. In infection, signs of inflammation in the wound and surrounding tissue are marked: the border of erythema widens, tissue temperature rises, the volume and purulence of exudate increase, odour may change, and the quality of granulation deteriorates.
This distinction is particularly critical in the diabetic foot. Colonisation is common on the foot; it is not an indication for every antibiotic-containing or silver-containing dressing. Suspected osteomyelitis, deep tissue infection, or a systemic inflammatory response is assessed separately. The sequence of first examination and referral is summarised under four headings in initial referral in diabetic foot wounds.
Biofilm and the chronic wound
IWII treats biofilm as an important heading in chronic wound management. Biofilm is a community of microorganisms organised within a protective matrix; no single clinical finding and no routine culture demonstrates biofilm definitively. Healing that stops unexpectedly, and a problem that recurs after appropriate care, can suggest the possibility of biofilm. Management includes appropriate cleansing and debridement, correction of the wound aetiology, and — where needed — planned reassessment of a time-limited topical antimicrobial approach. Systemic antibiotics are considered separately, and only where there is a clinical indication.
When is an antimicrobial dressing indicated?
Antimicrobial dressings — categories containing silver, iodine, polyhexamethylene biguanide (PHMB), or similar active agents — are considered once signs of local infection are confirmed, in line with the institutional protocol and guidance. Practical indications:
- Signs of local infection — new or increasing pain, delayed healing, deterioration of granulation tissue, erythema, increased warmth, or purulent exudate, when assessed together.
- Possible biofilm — where clinical problems recur and healing stalls despite appropriate standard care; as part of the cleansing and debridement plan.
- High infection risk — only in selected situations defined by the institutional protocol and the product’s instructions for use (IFU), with the rationale and review date recorded.
- Step-up plan — following clinical reassessment when standard care falls short, with a time-limited trial and criteria for stopping.
An antimicrobial dressing does not replace systemic antibiotics or surgical debridement. Where osteomyelitis, deep space infection, or sepsis is suspected, urgent management and specialist referral take priority. Inadequate perfusion makes infection control harder; where ischaemia and infection coexist, both are addressed without delay. This relationship is examined as two parallel pathways in critical limb ischaemia and wounds.
When is it not indicated?
In the situations below, routine selection of an antimicrobial dressing is generally not required:
- Colonisation alone — culture positive, no clinical inflammation.
- Contamination — transient microbial presence, brief and following debridement.
- Inadequate perfusion alone — ischaemia is not an indication for an antimicrobial dressing; but where ischaemia and infection coexist, both are addressed without delay.
- Proactive “preventive” use — moving to a silver- or iodine-containing dressing with no sign of infection is not an evidence-based routine.
In venous ulcers, oedema control and reduction of venous pressure are the core headings; signs of infection and arterial circulation are assessed at the same time. Measurements such as the ankle–brachial pressure index, toe pressure, or transcutaneous oxygen pressure guide the compression and wound care plan alongside clinical examination; the detail appears in perfusion assessment in wound care.
Sources
- International Wound Infection Institute (IWII). Wound Infection in Clinical Practice: Principles of Best Practice. 2022. Consensus document
- Lavery LA, et al. WHS guidelines update: Diabetic foot ulcer treatment guidelines. Wound Repair Regen. 2016. doi:10.1111/wrr.12391
- O’Donnell TF Jr, et al. Management of venous leg ulcers: clinical practice guidelines of the Society for Vascular Surgery and the American Venous Forum. J Vasc Surg. 2014. doi:10.1016/j.jvs.2014.04.049
- International Working Group on the Diabetic Foot / Infectious Diseases Society of America. Guidelines on the Diagnosis and Treatment of Diabetes-related Foot Infections. 2023. idsociety.org
- VascularVita: Before choosing a wound product · Wound care · Diabetic foot referral