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Managing wound infection requires a holistic process, from assessment strategies to determine the level and severity of bacteria present, to identifying and understanding a patient’s particular risk factors. This requires a team approach, bringing together clinicians with specific expertise, including certified wound ostomy and continence nurses (CWOCNs).
With wound treatment, it is important to understand that while bacteria and bacterial byproducts can disturb the normal orderly process of wound healing, the presence of microorganisms alone may not be a risk factor for infection. Low levels of bacteria can colonize a wound without injury to the host. In fact, the presence of low levels of bacteria can actually enhance some processes such as fibroplasia. (Robson, 1997) Bacteria may even aid in desloughing and stimulate inflammation. (Tonge, 1997)
Bacteria balance can be plotted along a continuum, from lowest level to a more severe state of infection. The type and level of bacterial presence should be taken into consideration when determining treatment.
The lowest level on the bacterial balance continuum is “contaminated.” A small number of non-adherent, non-replicating bacteria is present, but do not negatively impact healing. The next level is “colonized,” at which bacteria are replicating in colonies and adhere to the surface. The bacteria are non-invasive, however, and wounds heal.
A more severe level is “critically colonized.” Here bacteria replicate and begin to invade the wound. Subtle signs of infection can be detected, and healing is delayed. The most serious level is “infected.” Bacteria replicate and are deeply invasive. Classic signs and symptoms of infection can be identified. Wound infection occurs when the number of organisms exceeds the ability of local tissue defenses to handle them. (Peacock and Van Winkel, 1976)
When treating infection, the determining factors are not just the number of bacteria and the virulence of the organisms. Clinicians need to consider the patient, as well as the wound. Risk of infection typically increases with a large wound area, increased wound depth, degree of chronicity, anatomic location (e.g., distal extremity or perineal), presence of a foreign body, necrotic tissue, and reduced perfusion. In addition there are systemic factors in the patient that create a higher risk of infection in chronic wounds, such as vascular disease, edema, malnutrition, diabetes mellitus, alcoholism, prior surgery or radiation, use of corticosteroids or other drugs, and inherited immune defects.
Wound sampling is used to identify the type and number of bacteria. Procedures for both aerobic and anaerobic microorganisms should be used. Wounds identified for sampling encompass those that are clinically infected, and those that are non-healing or deteriorating without clinical signs of infection. Wound sampling may involve surface samples, tissue biopsy during surgical debridement procedures, and closed space fluid such as enclosed abscesses.
With surface samples, semi-quantitative swabs may provide meaningless information with regard to wound care decisions. However, swabs can serve as an important adjunct in managing chronic wounds. (Ratliff and Rodeheaver, 2002) Although a swab will not diagnose an infection, it will reveal the type of organisms, numbers of organisms, and sensitivity and resistance. More meaningful information can be obtained from swab specimens that are quantitatively processed in the laboratory. (Gardner, 2007)
Wound infection varies by severity and should be classified according to symptoms. Signs of a superficial infection include a non-healing area, bright red granulation tissue, friable and exuberant granulation, new areas of breakdown or necrosis, increased exudate, bridging of soft tissue and the epithelium, and foul odor. A deep wound infection is identified by pain, induration, erythema greater than two centimeters, wound breakdown, increased size or satellite areas, undermining or tunneling of area, probing to bone, and flu-like symptoms. A systemic infection may be present if, in addition to the symptoms of a deep wound infection, the patient exhibits fever, rigors, chills, hypotension, and multi-organ failure.
Treatment modalities for infection control should involve a four-pronged approach: host support, medical asepsis, cleansing and debriding, and antimicrobial therapy.
Strategies for a superficial infection include support for the patient’s defenses, cleansing and debriding the wound, antimicrobials, and possibly oral/IV antibiotics, depending upon the patient risk. Evaluation based on clinical findings is ongoing, and patient education is essential.
For a deep wound infection, further steps in addition to those for a superficial infection include use of a polymicrobial, use of oral or IV antibiotics, possible surgical debridement, and potentially infectious disease consultation, as well. For a systemic infection, steps in addition to those described above include hospitalization and IV antibiotics.
In general, bacterial control host support should be the primary management strategy in preventing and treating wound infection. This includes: environment support to explore lifestyle choices that affect the patient’s vulnerability to infection (e.g., adequate rest); systemic support to review the person’s physical and emotional vulnerability to infection; (Segerstrom and Miller, 2004) and local support to remove necrotic tissue to decrease the risk of infection.
Bacterial control is accomplished through wound cleansing and debridement. Debridement is the single most important action to reduce the level of bacterial contamination in chronic wounds. Bacteria thrive in devitalized tissue and exudate. (Rodeheaver, 2001) The choice of debridement must match the needs of the patient and the wound, the skill and practice ability of the clinicians, and available resources.
Cleansing solutions should not be toxic to healthy tissue. Enough mechanical force should be used to remove necrotic tissue, exudate, metabolic waste and dressing residue from the wound surface, but not enough to traumatize. (Campton-Johnston, 2001; White et al., 2001)
When treating and managing wound infection a team approach is the best response to bring together clinical expertise, including the specialized skills, training, and experience of CWOCNs. Through collaboration, significant savings in cost and time may be achieved, while providing prompt and appropriate treatment for the patient.
For more information, contact the Wound, Ostomy and Continence Nurses Society at www.wocn.org.
Kathleen Ozella is a member of the Wound, Ostomy and Continence Nurses’ Society (WOCN). She practices at St. Vincent Hospital in Worcester, Mass.
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Gardner SE, et al. Diagnostic validity of semiquantitative swab cultures. Wounds. 19(2):31-38. 2007.
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