Use of antimicrobial dressings Fran Whitehurst Clinical Nurse Specialist in Tissue Viability Conwy and Denbighshire NHS Trust

The infection continuum contaminated colonised critically colonised infected

The infection continuum CONTAMINATION means that bacteria are present but not multiplying COLONISATION means that bacteria are present and multiplying in a wound, but do not produce a host reaction CRITICAL COLONISATION means the bacteria are delaying healing but traditional signs of infection are absent INFECTION means that bacteria are present, multiplying and producing a host reaction

Chronic wounds and bacteria Bacteria will be found in all chronic wounds (Apart from when bacterial screening is requested) there is no need to swab unless infection or critical colonisation is suspected. Therefore we need to be able to identify signs/symptoms of critical colonisation and infection in a chronic wound.

How do you identify infection in a chronic wound? Clinical picture will tell us when a wound is infected Microbiological investigations will provide additional information quantitative qualitative

Clinical picture Traditional signs of infection Abscess Cellulitis (heat, erythema, tenderness) Purulent discharge

Quantitative (10 5 ) bacteria per gram of tissue or ml of body fluid. Traditionally seen as the critical bacterial burden. Microbiological investigations

Qualitative Looks at the type of bacteria. Research suggests that wound healing is impaired if more than 4 different identified.

Theory behind critical colonisation Bacteria in a wound provoke an inflammatory response However, a prolonged inflammatory response starts to have a detrimental effect on healing At this point, critical colonisation is said to occur - bacteria are delaying healing, but the traditional signs of infection are absent.

Identifying critical colonisation There is - delayed healing wound breakdown pain or tenderness increase in exudate friable granulation tissue pocketing or bridging discolouration unusual smell All other possible reasons for delayed healing, eg malnutrition underlying disease unrelieved pressure Inappropriate treatment –etc Have been excluded or addressed

Unhealthy/Healthy wound beds

Useful documents

Management of infected and critically colonised wounds Appropriate systemic antibiotics are needed for infected wounds, but are not generally recommended for critical colonisation. Address factors which compromise the immune system - eg malnutrition or unstable diabetes Prevent cross infection - hand washing, cleaning of baths and showers, no sharing emollients, towels etc

Wound dressings Topical antimicrobial dressings may be of use for a limited period. The rationale for use is to reduce the bacterial burden of the wound, to enhance healing, to reduce odour by removing the odour-producing bacteria and to reduce the risk of cross infection

Commonly used antimicrobials Chlorhexidine Honey Iodine Maggots Antibiotics Silver Cutimed Sorbact

How long should antimicrobial dressings be used? EWMA guidelines say – if no improvement in 7-10 days, patient should be reassessed Alternative causes of failure to progress (eg ischaemia) should be considered Issues relating to possible immuno- compromised status should be addressed If infection still likely, alternative antimicrobials should be selected

How long should they be used for? Antimicrobial dressings can be used short term to reduce the bioburden of the wound It is essential that the wound is formally reassessed after 2 weeks

Then what? If no improvement:- discontinue and seek other cause of failure to progress If wound improves:- antimicrobial dressing may be continued for up to 2 more weeks (total 4 weeks maximum), or may be discontinued depending on wound condition.

Possible problems Skin and wound bed may become stained black (silver) Some patients find antimicrobial dressings painful, and some have a tendency to stick Worries about bacteria becoming resistant to them In vitro keratinocyte toxicity to silver (not seen in clinical practice)

Example Week 1 Long standing venous leg ulcer. Patient is in compression bandaging Ulcer is sloughy, malodorous and non- healing Daily dressing changes needed Silver dressing commenced (under compression )

Week 2 Considerable improvement Granulation tissue appears much healthier Less odour, less exudate Needing twice weekly dressing changes

Week 4 Wound bed is almost 100% red granulation tissue Dressings changed once a week Silver dressing discontinued

Conclusion We need to be able to identify wound infection and critical colonisation Antimicrobial dressings may be a useful adjunct to systemic antibiotics for an infected wound They dressings may be useful in the treatment of critically colonised wounds Long term use is not recommended