Wound Bed Preparation: Bacterial Balance

Without a healthy wound bed, wound care products aren’t effective. But before such products can do their job, the wound bed must be prepared. The goal is a well vascularised, stable wound bed.

In order to achieve that, bacterial balance must be restored. Wounds already contain many organisms, but it is up to the clinician to recognize when a wound has become infected by assessing the wound bed and periwound tissue. (Wound bed preparation also requires the elimination of nonviable tissue, providing a moist environment and maintaining moisture balance, correction of cellular dysfunction, and restoration of biochemical balance, all of which we will discuss in the next four posts.) 

What variables affect the bacterial burden of a wound?

Four variables affect the bacterial burden of a wound: the amount of necrotic tissue, the number of microorganisms present, the bacterial virulence, and the host resistance. Host resistance is often the culprit, and can occur with conditions such as vascular disease, edema, and diabetes, as well as lifestyle issues including alcohol abuse, poor nutritional status, smoking, and immunosuppression/use of steroid medications. 

What are the local signs of infection?

Local signs of infection often include redness, warmth, edema, induration, and pain. These signs are also seen during the inflammatory and proliferative phase of wound healing, which can make it difficult to determine if the wound is infected. When any of these signs, in addition to purulent drainage, foul odor, discolored or friable granulation tissue, or tissue breakdown, are seen together, it is safe to say that bacterial infection at the wound site should be ruled out. 

How is infection determined?

 Clinical infection is determined by bacteria load; a load greater than 100,000 bacteria per gram of tissue or milliliter of fluid indicates the presence of infection. Infection is determined via tissue or punch biopsy, or with a swab culture using the Levine method. The Levine method involves rotating a swab culture over a 1-cm2 area of the wound with sufficient pressure to extract fluid from within the wound tissue. The swab must be taken after the wound is cleaned with normal saline and taken from viable tissue (bacteria growing in the tissue), not from dead or devitalized tissue.

How is wound infection treated?

When infection is present, treatment can include topical and adjunctive therapies to reduce the bacterial load, contain the exudate, and improve the wound’s granulation tissue. Oral or intravenous antibiotics may also be used to decrease the bacterial load. Because topical antimicrobials can lead to resistance and treatments must be applied frequently, antimicrobial wound dressings such as those containing silver and cadexemor iodine are a good option to manage wound bioburden.

 

If you are interested in learning more about wound care, or wish to become certified as a wound care specialist, visit us online at woundeducators.com to explore your options. 

 

Sources:

Chuck Gokoo, MD, CMO CWS, FACCWSa (2009). A Primer on Wound Bed Preparation. Journal of the American College of Certified Wound Specialists. 1, 35–39.

 

Cathy Thomas Hess, BSN, RN, CWOCN (2008). Meeting the Goal: Wound Bed Preparation. Advances in Skin & Wound Care (www.woundcarejournal.com). Vol 21, No. 7, Page 344.

 

Harriett Loehne, PT, DPT, CWS, FACCWS (2009). Managing Bacterial Burden with Silver Dressings. Wound Care Journal (www.woundcarejournal.com).

 

Kathryn Vowden RGN, DPSN(TV) & Peter Vowden MD, FRCS (2002). Wound Bed Preparation. Retrieved April 14 from www.worldwidewounds.com.