Infected Wounds

An infected wound is a localized defect or excavation of the skin or underlying soft tissue in which pathogenic organisms have invaded into viable tissue surrounding the wound. Infection of the wound triggers the body's immune response, causing inflammation and tissue damage, as well as slowing the healing process. Many infections will be self-contained and resolve on their own, such as a scratch or infected hair follicle. Other infections, if left untreated, can become more severe and require medical intervention.

The skin is the body's first line of defense, the surface of which is protected by a thin, acid film produced by the sebaceous glands called the acid mantle. This acid mantle is a dynamic barrier that regulates the skin's pH and maintains microorganisms called the normal flora that help prevent pathogens from entering the body. Pathogens will often displace some of the normal flora and colonize certain locations, but most of the time this does not lead to infection and does not stimulate an immune response. However, when the skin is broken or if the immune system becomes compromised, any of the microorganisms colonizing the skin or introduced to the wound can cause an infection. The microorganisms likely to infect a wound depend predominantly on what microorganisms are present on the skin, as well as the depth and location of the wound.

Symptoms of Infected Wounds

The clinical presentation of infected wounds includes fever, erythema, edema, induration, increased pain, and a change in drainage to a purulent nature. However, symptoms of infection in chronic wounds or debilitated patients may be more difficult to distinguish. In these cases, diagnosis may rely on non-specific symptoms such as loss of appetite, malaise, or decrease in glycemic control in diabetics.

Etiology

Most infected wounds are caused by bacterial colonization, originating either from the normal flora on the skin, or bacteria from other parts of the body or the outside environment. The most common infection-causing bacteria is Staphylococcus aureus and other types of staphylococci.

Risk Factors

• Poor circulation
• Diabetes
• Obesity
• Compromised or suppressed immune system
• Decreased mobility or immobility
• Malnutrition
• Poor hygiene

Complications

Complications of infected wounds can vary in range from local to systemic. The most severe local complication of an infected wound is stalled wound healing, resulting in a non-healing wound. This often results in significant pain, discomfort and psychological detriment for the patient. Systemic complications can include cellulitis (bacterial infection of the dermal or subcutaneous layers of skin), osteomyelitis (bacterial infection of the bone or bone marrow) or septicemia (bacterial presence in the blood that can lead to a whole-body inflammatory state).

Diagnostic Studies

• Bacterial culture
• Gram stain
• Antimicrobial susceptibility
• Fungal culture
• Blood culture

Treatments & Interventions for Infected Wounds

The following precautions can help minimize the risk of developing infected wounds in at-risk patients and to minimize complications in patients already exhibiting symptoms:

• Prompt and proper wound cleansing to reduce bioburden
• Maintaining proper nutrition and hydration

Approaches to treatment can be broken down by whether the infection is systemic or localized just to the wound area. Systemic treatment often will call for oral antibiotics, the specific type determined by microbiological investigation and local infection control protocols.

Localized infections can often be treated with topical antibiotics. Drainage or debridement may be necessary to remove slough and devitalized tissue, as these slow wound healing and can affect the efficiency of topical antibiotics. Antimicbrobial dressings, including those that use silver technology, may be used to help reduce bioburden. Antibiotics, whether topical or systemic, should only be used under the explicit direction of a physician.

Image Source: Medetec (www.medetec.co.uk). Used with permission.

References

American Association of Clinical Chemistry. Wound and Skin Infections. Lab Tests Online. http://labtestsonline.org/understanding/conditions/wound-infections. Updated July 12, 2012. Accessed September 19, 2012.

Collier M. Recognition and management of wound infections. World Wide Wounds. http://www.worldwidewounds.com/2004/january/Collier/Management-of-Wound-.... Updated January 2004. Accessed September 19, 2012.

HealthNews.org. Infected Wounds. Wound Care Centers. http://www.woundcarecenters.org/wound-types/infected-wounds.html. Accessed September 19, 2012.

McCulloch, JM, Kloth LC. Wound Healing: Evidence-based Management. 4th ed. Philadelphia, PA: F.A. Davis Company; 2010: 5, 109.

O'Dell ML. Skin and Wound Infections: An Overview. Am Fam Physician 1998;57(10):2424-2432. http://www.aafp.org/afp/1998/0515/p2424.html. Accessed September 19, 2012.

World Union of Wound Healing Societies (WUWHS). Principles of best practice: Wound infection in clinical practice. An international consensus. London: MEP Ltd, 2008. Available at: http://www.woundsinternational.com/pdf/content_31.pdf