Clinical Blog

Wound Management Series: How to swab wounds correctly and recognise wound infection

Wound Swab
Valerie Dowley, RGN, BSc (Hons)
Independent Tissue Viability Nurse Specialist
Read Part 2: Picking the correct wound dressing

Part 1: How to swab wounds correctly and recognise wound infection

Valerie Dowley, Independent Tissue Viability Specialist

Timely recognition and effective response to wound infection has always been a challenge and given the increasing complexities of patients who often suffer with multiple comorbidities, early identification and treatment is vital. According to Woo, 2024, there are too many variations and uncertainty in clinical practice regarding how to interpret the signs and symptoms of wound infection, and then linking them to an effective decision-making process that has the best possible outcome for both wound and patient (Woo et al, 2024. Jones, 2018).

As most wound care in the UK is delivered by Nurses, Nursing Associates or Health Care Assistants, there is a duty of care (NMC, 2018) to ensure that the clinician taking responsibility for the management of the wound has the knowledge, and their skills competencies are up to date in line with evidence-based practice.

The National Wound Care Core Capability Framework for England “sets a standard for all levels of the multi-professional workforce involved in wound care, whether as a gatekeeper to more specialised service, as an expert clinician working within such services, or as someone providing initial or ongoing wound care. It supports practitioners in developing and providing evidence of their knowledge and skills, enabling the highest standards of practice as well as providing a structure for career and role development within wound care”. (skillsforhealth, 2021)

The journey to developing a wound infection

International Wound Infection Institute (IWII) (2022, pg. 8) describes a wound infection as ‘the invasion of a wound by proliferating microorganisms to a level that invokes a local, spreading, and/or systemic response in the host’. While Swanson et al, in 2006 puts it more simply as, ‘impairment of wound healing by bacteria’.

It is important to highlight that not all wounds will go on to become infected and the risk of developing a wound infection is linked to multiple factors such as:

  • the patient’s immune response and comorbidities
  • type and duration of the wound
  • cause of the wound alongside environmental factors such as unhygienic conditions, inadequate hand hygiene, or Aseptic Non-Touch Technique (ANTT)
  • inadequate management of wound symptoms such as moisture, biofilm or devitalised tissue

There is no such thing as a sterile wound, so it is important to remember that all wounds have transient microorganisms present, and it is usually the skin’s own flora which is responsible for the initial contamination of a wound (McCoulough, 2020).  

Contamination refers to the presence of bacteria in the wound, but they are not multiplying and causing any host response or any delay in healing.

Colonisation refers to bacteria which are beginning to multiply in the wound but still not causing a host reaction or delaying wound healing.

Local infection happens when colonisation is not brought under control, and the proliferation of the bacteria overwhelms the host’s defences and is now causing localised changes to the wound bed.

Certain comorbidities can mask the increasing signs of wound infection such as immunosuppressed or Diabetic patients.

  • Erythema (redness) to the peri wound tissue of < 2cm (it is difficult to identify erythema on darker skin tones, and it may appear as discolouration of tissue alongside the other symptoms)
  • Increase in exudate
  • Increase in wound odour
  • Increase in pain to the wound bed or surrounding tissue
  • Bleeding or fragile granulation tissue
  • Failure to epithelialise (grow the top layer of skin over the wound)

Spreading infection is when the microorganisms have invaded the wound and surrounding tissue and may involve deeper tissue.

  • Local swelling / oedema
  • Wound breakdown / getting bigger
  • Presence of new necrotic or sloughy tissue
  • Purulent discharge
  • Spreading inflammation or tracking cellulitis

Systemic infection is when the bacteria travels around the body within the blood or lymphatic system, and toxins are released into deeper tissue, muscle, organs, and body cavities, causing organ disfunction:

  • Loss of appetite
  • Malaise
  • Lethargy
  • Fever / pyrexia
  • Sepsis

(IWII, 2022, Rutter, 2018. Sandoz, 2022, Jones, 2018)

What should you do if you suspect a wound infection?

When a wound infection is suspected, it is important to action the following:

  • Establish if there are any systemic signs though routine clinical observations – temperature, pulse, respiratory rate, blood pressure, level of consciousness and oxygen saturation in line with The National Early Warning Score 2 (NEWS2) (NICE, 2016).
  • Complete a new, holistic wound assessment, including documenting the condition of the wound itself, wound measurements, presence of any new devitalised tissue, malodour or pain.
  • Escalate your concerns to the senior Clinical Lead and inform the GP. Ensure you are familiar with your Wound Management Policy.
  • Select appropriate products from your local wound dressing formulary, to manage the symptoms of the wound such as: superabsorbent pads for increased exudate, antimicrobial primary dressings to reduce microbial activity on the surface of the wound.
  • Seek advice from specialist services such as District Nursing Teams, Tissue Viability, Podiatry, Vascular Nurse Specialists, if you are not feeling confident in your management plans.
  • Document your assessments, choices, and rationale clearly and in a timely manner.

Should I always swab wounds for infection?

Wound swabbing is a simple investigatory, non-invasive and convenient procedure which in practice is carried out differently, or with wide variations, in most health settings.  Undertaking a swab would be considered part of the core competencies of all registered nurses and therefore the nurse performing this is accountable for ensuring their knowledge and skills are updated and in line with current best practice (NMC, 2018).

Clinicians must make sure they complete the paperwork in full, or in as much detail as possible, so that the microbiologist can culture the specimen correctly and offer the most appropriate treatment. It is also the responsibility of the clinician who takes the swab to follow up on the results, either with the patient’s GP, or the hospital (Patten, 2010).

A wound swab alone will not identify an infection as it only provides an idea of the number of microorganisms present within the wound and then identifies the bacteria with the highest numbers which it will presume is the causative pathogen. Therefore, it is important, since all wounds will have some microorganisms present, that wound swabbing is only carried out if there are clinical signs of infection or wound deterioration, as described in the last paragraph.

Wound swabbing techniques

In a randomised controlled trial (RTC) conducted by Angel et al (2011), it was shown that the Levine Technique is superior to the traditional Z Technique, as it detected more organisms in both acute and chronic wounds. This is achieved by expressing fluid from the wound bed and capturing a greater number of microorganisms from the surface and just below the surface of the wound bed tissue.

Wound swabbing should always be undertaken using Aseptic Non-Touch Technique (ANTT). There is a wealth of resources and posters on ANTT available from https://www.antt.org/ free of charge. Some of these can be displayed in clinical areas to ensure staff are regularly updated.

Hand-washing and local aseptic technique to prevent infection 

Hand hygiene remains the key barrier to cross infection and is one of the easiest ways to protect yourself and your patients from cross contamination (NHS, 2023).

In conclusion

It is very important that all healthcare professionals responsible for the assessment and day to day management of all types of wounds are aware of the signs and symptoms of wound infection, know how to swab a wound correctly, and when to escalate their concerns. If the day-to-day management of wounds is being delegated to nursing support staff, then it is the responsibility of the Registered Nurse to ensure that the person they are delegating to is up to date with their knowledge and clinical skills, and is confident in their ability to recognise wound infection or wound deterioration.

The next article in this series will look at appropriate wound dressing selection. 

Please cite as: OSKA Care Ltd. (March 2025). Wound Management Series: How to swab wounds correctly and recognise wound infection. Havant, Portsmouth: OSKA Care Ltd.

References

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