Epidemiology

Infected chronic wounds are one of the biggest challenges to healthcare systems because they are difficult to heal and expensive to treat. In the UK there are approximately 200,000 individuals suffering from a chronic wound (mostly leg, pressure, and diabetic foot ulcers) at any one time. The annual direct cost to the NHS of caring for patients with chronic wounds is about £4 billion. The most severe ulcers are difficult to treat and can lead to life-threatening infections and sepsis; UK government statistics for 2011 showed bed sores to be a contributing factor in almost 800 patient deaths. Furthermore, with an aging population and rapidly increasing incidence of diabetes, people suffering from infected chronic wounds and the consequent cost to the NHS are set to increase further (34).

 

Definitions and Aetiology

There is a fine balance between environmental and skin flora. This balance maintains an equilibrium determined by conditions such as skin moisture and pH balance until there is a break in the skin. Infection in a wound is a manifestation of a disturbed host-bacteria equilibrium in favour of the bacteria. This elicits a systemic response and inhibits the wound healing process.

The main routes of entry for bacteria to cause infection are: self-contamination by scratching, directly from the surrounding skin flora or GI tract (often faecal organisms), airborne contamination, skin squames or water droplets, contact contamination from unwashed hands, clothing, equipment and contact with skin of others (35).

 

An infection is defined as the infiltration and rapid increase of microorganisms such as bacteria, viruses, and parasites that are normally absent within the body. Infected wounds are caused by microorganisms that evade the victims immunological defences, establish themselves within tissues and successfully multiply. (This differs from colonised wounds which is multiplication of organisms without host reaction, Vs contamination which occurs when organisms are present but not multiplying or clinically affecting the host) (35).

 

Identifying Infected Wounds

Erythema around the wound and pyrexia, are the obvious signs of clinical infection but diabetic patients, those with rheumatoid arthritis or who are elderly may present with subclinical infections. This should be suspected in a non-healing wound that’s steadily increasing in size, etc. It may prompt a swab and swab results demonstrating a bacterial count greater than 10^5 indicates possible infection or an increased potential (35).