Infection / Inflammation

Chronic wounds contain a variety of microbial flora, which may be derived from the host, the environment, or both sources. As a result, the presence of microorganisms in a chronic wound is not, by itself, an indicator of infection.

Wound Infection

Chronic wounds contain a variety of microbial flora, which may be derived from the host, the environment, or both sources. As a result, the presence of microorganisms in a chronic wound is not, by itself, an indicator of infection. The microbial population of a chronic wound can be categorized as follows:

  • Contamination: Superficial non-replicating bacteria with no host response.
  • Colonization: Superficial replicating bacteria with no host injury. Moderate wound colonization with nonpathogenic skin flora may accelerate healing.
  • Critical colonization: Replicating bacteria within the surface wound compartment, which delay or stop healing. Other clinical signs of host injury may be present.
  • Infection: Replicating bacteria within the deep wound compartment. Tissue invasion occurs when microbial burden or virulence overwhelms host resistance. Clinical signs indicate host injury.

Host resistance is the most important determinant of chronic wound infection. Factors affecting host resistance include the following:

Wound size and location: Larger wounds and sites that are difficult to keep clean, such as plantar and perineal areas, have a greater risk of infection. Wound age: Wounds older than 6 weeks are associated with polymicrobial flora and are more likely to develop infection of deep tissue structures and bone. Perfusion: Inadequate oxygenation favours microbial proliferation, increases the risk of infection, and decreases the likelihood of healing. Presence of devitalized tissue or foreign bodies: Devitalized tissue is a source of nutrients for bacteria. Foreign bodies of any type, including orthopedic prostheses, can harbour microorganisms. Both predispose to the development of infection.

Systemic and personal factors affecting the risk of infection include the following:

Behaviour, such as lack of adherence to treatment, persistent smoking, alcohol abuse Socioeconomic status, which may preclude purchase of appropriate treatment regimens or devices Comorbidites affecting metabolic, nutritional or immune function, or vascular perfusion may increase the risk of infection.

Diagnosis of infection is based on clinical evaluation and supported by microbiological data. Signs of infection include delayed healing; increased serous drainage and inflammation; increased tenderness; friable or bleeding granulation tissue; foul odour; and increased wound breakdown. Moderately severely infected wounds may also have a rim of cellulitis with increased erythema, swelling and local skin temperature. Severe infection may be associated with systemic signs of sepsis.

Topical or systemic antibiotic therapy has not been shown to be beneficial in the absence of critical colonization or wound infection. Topical antibiotic therapy may be appropriate for critically colonized wounds, whereas systemic therapy is indicated for patients with infected chronic wounds. Topical agents may be applied when systemic antibiotic therapy is used. Individuals with diabetes, who have a greater risk of limb-threatening sepsis, may benefit from early systemic antibiotic therapy, to prevent critical colonization from developing into infection.

Initial empiric systemic antibiotic therapy may be individualized once detailed culture and sensitivity information is available. Gram-positive organisms usually cause infections in wounds that have been present for less than 1 month, whereas polymicrobial infection is usually found in wounds that have been present for more than 1 month. Infections in wounds in immunosuppressed individuals should be assumed to be polymicrobial. Broad-spectrum antibiotic therapy is appropriate for suspected infection in patients with diabetes, as diabetic foot infections are polymicrobial.

Specific microbiologic data are required to select antibiotic therapy for extensive and longstanding infection. As the likelihood of encountering resistant organisms is increasing, resistance should be considered when an infected wound does not respond to appropriate antimicrobial treatment. Repeat culture and sensitivity can identify the resistant organism and treatment options.

Identify and Treat the Cause Level of Evidence
1 Implement a regular wound assessment protocol that allows early identification of critical colonization or infection. Not Assessed
2 Diagnose infection or critical colonization based on clinical assessment, and support the diagnosis with microbiological information. Not Assessed
Address patient-centered Concerns Level of Evidence
3 Communicate (patients, family, caregivers) to establish a social support system with realistic expectations for healing and to prevent ulcer recurrences. Not Assessed
4 Assess / control pain to optimize activities of daily living. Not Assessed
Provide Local Wound Care Level of Evidence
5 Optimize the wound healing environment through control of bacterial burden and infection. Not Assessed
6 Do not use antibiotics to treat contaminated or colonized wounds. Not Assessed
7 Treat critically colonized wounds with topical antibiotics, unless patient factors support early initiation of systemic antibiotic therapy. Not Assessed
8 Initiate empiric systemic antibiotic therapy for infected wounds and critically colonized wounds in patients with diabetes, and individualize therapy once culture and sensitivity data are available. Not Assessed
Provide Organizational Support Level of Evidence
9 Consult appropriate disciplines to maximize healing (e.g. dietary, physiotherapy, surgery, community resources etc., as required). Not Assessed

Essential Publications

0 Infection prevention Quality Indicator Type: CPG (Clinical Practice Guideline)
NICE Infection Control Prevention of healthcare-associated infections in primary and community care, June 2003
This paper is extremely useful because it provides comprehensive and detailed recommendations on how to prevent infections in primary and secondary care. It acts as a stand-alone document, and its recommendations can be easily implemented into practice and be used to prevent wound infections.
1 Infection – diabetic foot Quality Indicator Type: CPG (Clinical Practice Guideline)
Lipsky BA. A report from the international consensus on diagnosing and treating the infected diabetic foot. Diabetes/Metabolism Research and Reviews 2004; 20(Suppl 1): S68-S77.
his guideline is useful for practitioners seeking to prevent or to treat diabetic foot infections. The most useful component of this guideline is its practice algorithm, which details a comprehensive approach to managing the diabetic foot.
3 Infection – diabetic foot Quality Indicator Type: Systematic review
Nelson EA, O’Meara S, Craig D, Iglesias C, Golder S, Dalton J, Claxton K, Bell-Syer SEM, Jude E, Dowson C, Gadsby R, O’Hare P, Powell J. A series of systematic reviews to inform a decision analysis for sampling and treating infected diabetic foot ulcers. Health Technol Assess 2006;10(12).
The systematic review’s value lies in its emphasis on the need for future research. It demonstrates that the current techniques for identifying infections are unreliable. Furthermore, it shows that there is no evidence demonstrating which antibiotics are most effective in treatment of infections, and how they should be administered. This systematic review identifies these areas as essential for future research.
4 Diagnosis of Infection Quality Indicator Type: Systematic review
O’Meara S, Nelson EA, Golder S, Dalton JE, Craig G, Iglesias C. Systematic reviews of methods to diagnose infection in foot ulcers in diabetes. Diabet. Med. 23, 341–347 (2006)
This systematic review of cross sectional studies was conducted to explore the diagnostic performance of clinical examination, sample acquisition and sample analysis in infected foot ulcers in diabetes. The study is important for demonstrating that the evidence is weak. Thus, we are encouraged to determine better methods of diagnosing infection in foot ulceration in people with diabetes.
5 Infection risk factors Quality Indicator Type: Prospective Correlation study
Lavery LA, Armstrong DG, Wunderlich RP, Mohler MJ, Wendel CS, Lipsky BA. Risk factors for foot infections in individuals with diabetes. Diabetes Care 2006;29:1288-1293.
This study analyzes potential risk factors for foot infection in diabetic patients. It identifies that traumatic foot wounds, particularly those that are chronic, deep, recurrent, or associated with peripheral vascular disease are at greatest risk for infections. This implies that clinicians who wish to diagnose foot infections should be cognizant of these conditions.
6 Infection – topical triple antibiotics Quality Indicator Type: Narrative Review
Diehr S, Hamp A, Jamieson B. Do topical antibiotics improve wound healing? Journal of Family Practice 2007;56;140-143.
This narrative review provides a comparison of topical triple-antibiotic ointments and petrolatum control in minor contaminated wounds. It demonstrates that topical antibiotics are effective in the treatment of minor contaminated wounds. It also asserts that future research is necessary to examine their effects on larger chronic wounds.
7 Infection Quality Indicator Type: CPG (Clinical Practice Guideline)
Stevens DL, Bisno AL, Chambers HF, Everett ED, Dellinger P, Goldstein EJ, Gorbach SL, Hirschmann JV, Kaplan EL, Montoya JG, Wade JC. Practice guidelines for the diagnosis and management of skin and soft-tissue infections. Clin Infect Dis 2005 Nov 15;41(10):1373-406.
This guideline is effective in providing recommendations for diagnosing and treating soft-tissue infections. It also presents an algorithm that can quickly and effectively be implemented into practice. Consequently, the guideline is a very useful reference for clinical practice.
8 Infection – topical silver Quality Indicator Type: Systematic review
Vermeulen H, van Hattem JM, Storm-Versloot MN, Ubbink DT. Topical silver for treating infected wounds. Cochrane Database of Systematic Reviews 2007, Issue 1. Art. No.: CD005486. DOI: 10.1002/14651858.CD005486.pub2.
Silver containing agents are advocated for the treatment of infected or contaminated wounds. In this systematic review, no significant difference in complete wound healing was found for subjects treated with silver containing agents compared with standard foam dressings. This review therefore did not provide conclusive evidence to support the use of silver containing agents; however, it is important because it elucidates the need for more well-designed studies on this topic.
9 Infection – pre-discharge patient education of surgical site surveillance Quality Indicator Type: RCT
Whitby M, McLaws ML, Doidge S, Collopy B. Post-discharge surgical site surveillance: does patient education improve reliability of diagnosis?. J Hosp Infect 2007;66(3):237-242.
This paper raises doubts about the benefits of pre-discharge patient education regarding surgical-site infections. The study demonstrates that patients who receive education over-diagnose wound infections. This not only has profound implications on clinical practice, but it also suggests that using patient self-diagnosis as a tool for future studies is an unreliable technique.
10 Infection – effectiveness of wound cleansing Quality Indicator Type: Systematic review
Fernandez R, Griffiths R, Ussia C. Effectiveness of Solutions, Techniques and Pressure in Wound Cleansing. JBI Reports 2004; 2(7): 231-70.
This well-conducted systematic review examined different methods of treating wounds to prevent infection and promote healing. The study found that cleansing with water and saline produced no significant difference. Further research is required to compare different techniques.
11 Infection/Inflammation Quality Indicator Type: Narrative Review
Sibbald RG, Woo K, Ayello EA. Increased bacterial burden and infection: The story of NERDS and STONES. Adv Skin Wound Care 2006;19(8):447-61.
An overview of wound infection and inflammation, in particular bacterial balance, as well as a guide to the assessment and treatment of chronic wounds is presented to practitioners in this article. The effect of bacteria on the wound is examined extensively and recommendations that consider bacterial balance were provided. The mnemonics NERDS, for superficial infection, and STONES, for deep infection, are identified as helpful wound infection assessment tools. The recommendations presented in this paper provide practitioners with a methodical approach to optimize wound care, but also stresses a patient-centered care model.
12 Infection and Inflammation Quality Indicator Type: Narrative Review
Sibbald RG, Orsted H, Schultz GS, Coutts P, Keast D (2003). Preparing the Wound Bed 2003: Focus on Infection and Inflammation. Ostomy/Wound Management 49(11): 24-51.
This article is an update of the wound bed preparation model based on the evidence base and expert opinion regarding infection. The initial assessment of a chronic wound must include an evaluation of the vascular supply to ensure blood flow is adequate. The concept of TIME – tissue debridement, control of inflammation or infection, moisture balance and edge effect is presented as an approach to local wound care. This article is a good summary of this topic.
13 Bacteria and Wound Healing Quality Indicator Type: Narrative Review
Edwards R and Harding KG (2004). Bacteria and Wound Healing. Current Opinion in Infectious Disease 17: 91-96.
An understanding of the physiology and interactions within multi-species biofilms may aid the development of more effective methods of treating infected and poorly healing wounds. Erythromycin may have an inhibitory effect on biofilm formation, and macrolide antibiotic combinations can induce invasion of phagocytes into biofilms. The addition of topical antimicrobials may reduce the bioburden further and improve the wound healing response.