A wound 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.

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

It’s important 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.

A wound’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

It can 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

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

If you 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 the surface substance and underlying non-viable or unhealthy tissue. This will disrupt the microbial burden and prevent biofilmfrom 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.

Detecting biofilm can be challenging, due to the following factors:

• Biofilm are microscopic structures, which are invisible to the naked eye. So you need to use a high-powered microscope to detect them.
• In a clinical setting, the best detection method is a tissue biopsy. However, biofilm are small and unequally distributed in the wound bed. A wound may have different species of biofilm, and they are typically scattered around in small, isolated, single-species islands. That’s why they can be easy to miss.

Given the expense and time involved in tissue biopsy and microscopy, most clinician diagnose biofilm by identifying the common signs of wound infection. Some of these signs are^2,4:

• sloughy tissue
• increased levels of exudate
• poor granulation / friable hyper granulation
• malodour
• delayed healing

If a wound still shows these signs of infection after it has been managed correctly and the patient has received appropriate health support, biofilm may be present.

Try asking yourself the following questions²:

• Have all appropriate diagnostic and therapeutic measures been followed?
• Is the wound failing to heal as expected?
• Does the wound show signs of local infection or inflammation?

If you answer ‘Yes’ to at least 2 of these questions, it would be clinically relevant to treat for biofilm.