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What is wound infection?

Awound is considered infected when microorganisms that damage local tissue and delay wound healing are present.1

The presence of microorganisms triggers an immune response in the patient. Whether or not this response is successful depends on a balance of two things:

  • the strength of the patient’s immune system; and
  • the amount and virulence of the pathogens.


What causes wound infection?

When the amount and virulence of the pathogens are too much for the patient’s immune system to handle, the wound becomes infected.2

What role do microorganisms play in a wound?

It’simportant to note that all wounds contain microorganisms, and their presence does not necessarily mean the wound is infected. Keep in mind that:

  • a wound’s bacterial status can change depending on local, environmental and systemic factors; and
  • the transition from non-infected to infected wounds is often gradual.

What are the five stages of wound infection?

Awound’s microbial balance can be described as a continuum.1 There is a gradual increase in the number and virulence of microorganisms. As this occurs, the patient’s immune system responds accordingly. The figure below shows the five stages of wound infection:

  • Contamination
  • Colonisation
  • Local infection
  • Spreading infection
  • Systemic infection


The illustration here also shows when you should suspect the presence of biofilm, and the recommended intervention for each wound infection stage.

How can you tell a wound is infected?

Itcan be challenging to identify infection in chronic wounds. By performing a holistic wound assessment, you can evaluate the patient’s risk of infection. That will allow you to proactively manage the wound to reduce the risk of infection.3


If you don’t have access to modern microscopy tests to identify the organism causing the infection, you can use the following approach:


  1. Check for clinical signs and symptoms.
  2. Take a wound culture to identify the causative organisms and their potential resistance to antibiotics.3


What are the clinical signs of wound infection?

In the chart, you’ll see a list of the clinical signs and symptoms of local and systemic infections that you need to look out for when assessing the wound.2

How do you treat an infection?

Ifyou suspect an infection, your immediate goal is to reduce the bioburden in the wound.3 You can do this by:

  • therapeutic cleansing of the wound at each dressing change;
  • aggressive debriding of the surface substance and underlying non-viable or unhealthy tissue. This will disrupt the microbial burden and prevent biofilm from reoccurring;3 and
  • monitor the wound’s progress and reassess it continually to see if the wound is meeting your treatment goals. You should do this at least once a week or, optimally, at each dressing change.4


Treating specific types of infection


If there are signs of local wound infection, you can use topical antimicrobials. If the infection is spreading beyond the wound area, you will need to use systemic antimicrobials.

If there are signs of a systemic infection, consult a physician or wound specialist immediately.

Day 1

Day 2

Day 40

Day 131

The healing process of an infected wound over the course of 131 days

  1. International Wound Infection Institute (IWII) Wound infection in clinical practice. Wounds International 2016.
  2. Keast, David & Swanson, Terry. White paper – A practical summary for the management of wound infections and biofilm, Coloplast 2020
  3. Swanson, Terry. Keast, David. Bain, Kimberly & Mark. Preventing and treating infection in wounds: translating evidence and recommendations into practice. Wounds International 2020. Vol 11, issue 4
  4. Dowsett et al. (2020). Closing the gap between the evidence and clinical practice – a consensus report on exudate management (11(3))

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